
-■i 



Book__£S 



A 
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TREATISE 






ON THE 






ORIGIN, PROGRESSIVE IMPROVEMENT, 



AND 



PRESENT STATE 



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OF THE 



MANUFACTURE 



OF 



PORCELAIN AND GLASS. 



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CAREY & LEA— CHESTNUT STREET. 
1832. 



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BY TP a MQp^i|^ 






; 



LIST OF WOOD ENGRAVINGS. 



PORCELAIN. 



Page 

1. Throwing • 48 

2. Biscuit Kiln French Improvement • . 58 

3. Do. do. ib. 

4. Do. do. 59 

5. Making Tobacco Pipes, Roll 87 

6. Do. do. Needle ib. 

7. Do. do. Mould ib. 

8. Do. do. Kiln. ......... 88 



GLASS. 



1. Double Furnace . 128 

2. Glass Pot or Crucible 130 

3. Gathering Rod 137 

4. Blowing ib. 

5. Pontil 138 

6. Transferring from Gathering Rod to Pontil ib. 

7. Procello 139 

8. Fashioning ib. 

9. Annealing Oven, front view 142 

10. Blowing Crown Glass 146 

11. Circular Plate 147 

12. Casting Plate Glass 160 

13. Blowing do. Gathering 167 

14. Do. do. Cylinder ib. 

15. Do. do. Punching 168 

16. Do. do. Opening ib. 

17. Do. do. do ib. 

18. Do. do. Cutting ib. 

19. Do. do. Transferring 169 

20. Do. do. Opening ib. 

21. Do. do. Cutting ib. 

22. Do. do. Spreading . . 170 

23. Thermometer Tubes, Drawing 176 

A2 



CONTENTS. 

PART I. 
PORCELAIN MANUFACTURE. 

CHAPTER I. 

HISTORICAL NOTICES OF THE RISE AND PROGRESS OF POTTERIES 

AND THE PORCELAIN MANUFACTURE. 

Probable Origin of the Art.— Ancient Brick-making.— Roman Bricks.— 
The Potter's Wheel, an Implement of high Antiquity.— Indian Earth- 
enware. — Roman Water-pipes. — Introduced into Britain. — Remains 
of Ancient Pottery in the Kingdom. — Roman Potteries in Stafford- 
shire. — Earthenware made in an Island formerly existing near Mar- 
gate.— Antiquity of the Art in the East. — Porcelain first brought to 
Rome. — Figures found with Egyptian Mummies. — China Wares 
brought by Portuguese Traders. — Erroneous Notions concerning their 
Composition. — Corrected by Pere d'Entrecolles. — Discovery by De 
Botticher in Saxony. — Manufacture attempted in France. — Investiga- 
tions of Reaumur. — Proper Materials discovered in France. — Jonas 
Han way's Account of Collection at Dresden. — Works established at 
Berlin. — English Potteries. — Dr. Plot's Account. — Improvements in 
Crazing. — White Stoneware. — Advantages of Mr. Wedgwood's Im- 
provements. — Large Exportations by Mr. Wedgwood. — His principal 
Inventions. — Characteristics of true Porcelain. — First made by Mr. 
Cookworthy in England. — Importance of the Manufacture. — Porce- 
lain of Derby. — Of Coalport. — Of Worcester. — Of Rotherham. — Duty 
on Stoneware. — Its Unproductiveness and Impolicy Page 17 

CHAP. II. 

GENERAL DESCRIPTION OF INGREDIENTS USED IN THE 

MANUFACTURE. 

Different Branches of the Art. — Ingredients used. — Properties of Alu- 
mina. — Its Infusibility. — Contraction when exposed to Heat. — Wedg- 
wood's Pyrometer.— Composition of Gems. — Great Abundance of 
Clay. — Properties of Silica. — Its great Abundance. — 6ea Sand. — In- 
capable of artificial Solution in Water. — Dissolved naturally. — Springs 
at Carlsbad. — Boiling Fountain in Iceland. — Fusion of Silex. — Kinds 
of Clay used in Potteries. — Their various Merits. — China Clay of 
Cornwall. — Mode of its Preparation. — Its Analysis. — Cornish Fel- 
spar. — Its Fusibility. — Steatite. — Earth of Baudissero. — Its Analysis. 
— Cornish Sopestone. — Spuma Maris. — Its Employment in Porcelain 
Works in Spain 33 



V1U CONTENTS. 

CHAP. III. 
ON THE PREPARATION OF MATERIALS. 

Dilution of Clay. — Chemical Examination of Water necessary.— Rain 
Water. — Carefulness of German Manufacturers. — Blunging. — Ma- 
chinery. Preparing Flints. Burning. — Baking. — Grinding. — Dry 

grinding. — Brindley's improved Mill. — Chert. — Care required in se- 
lecting Grinding Stones. — Dilution of Flint Powder. — Affinity of 
Alumina for Silica. — Slip.— Slip-kiln. — Method of evaporating super- 
fluous Moisture. — Working the Paste. — Time necessary for temper- 
ing it. — Proportions wherein Clay and Flint are united. — Difficulty 
of ascertaining this. — Slapping. — French Manufactures. — Proportions 
of Ingredients used by them. — Kao-lin. — Flint. — Gypsum. — Broken 
Porcelain. — Calcined Bones. — Tender Porcelain. — Its Composition. 
— Porcelain Earth used in Berlin. — French Potters buy their Ma- 
terials ready mixed. — Advantages of this Plan. — Ineligible in Eng- 
land 40 

CHAP. IV. 

ON THE FORMATION OF UTENSILS. 

Throwing. — Potter's Lathe. — Thrower.— Mode of Proceeding. — Pro- 
files. — Slurry. — Gauges. — Turning Lathe. — Turning and Smoothing. 
— Moulding Dishes, &c. — Tools. — Steam Machinery. — Engine Lathe. 
— Milled Edges. — Handler. — Formation of Handles, Spouts, &c. — 
Pressing. — Small Ornamental Figures. — Mode of affixing them. — 
Method of making Moulds. — Boiled Plaster. — Great Use of Gypsum 
in making Moulds. — Stoves. — Modelling. — Qualifications requisite 
for a Modeller. — Increasing Skill of Artists. — Fostered by Wedg- 
wood. — Mould-maker. — Method of his working. — Casting. — Careful- 
ness required in Drying 48 

CHAP. V. 

ON THE PROCESSES OF FIRING AND GLAZING. 

Seggars. — Proper Materials for these wanting in England. — Not so in 
France. — Nungarrow Work. — Why discontinued. — Great Estimation 
of its Wares. — Cause of Superiority. — Use of Seggars. — Their Forms. 
— Mode of using them. — Sevres Manufactory. — Improved Furnace. 
— Its Advantages. — Description. — Chinese Method of Firing. — Con- 
struction of their Kilns. — Care required in Baking. — Duration of Pro- 
cess. — Oven-man. — Trial Pieces. — Annealing. — Biscuit. — Wine-cool- 
ers. — Glazing. — Composition of Raw Glazes. — Bad Effects of some of 
these. — To the Public. — To the Workman.— Pernicious Use of Ardent 
Spirits. — Glazes invented by M. Chaptal. — By Mr. Rose. — Porcelain 
Glazes. — French Glazes. — Pallissy. — His Experiments in Enamel- 



CONTENTS. IX 

ling. — His Perseverance and Sufferings. — His Success, and continued 
Firmness under Persecution. — Inferior Glazes. — Low-priced Wares. 
— Gloss Oven. — Regulation of Temperature. — Qualities that deter- 
mine the Excellence of Porcelain. — Stone Ware. — Its Composition. — 
Lambeth Potteries. — Modes of Glazing 55 

CHAP. VI. 

ON THE ART OP APPLYING COLORS AND ENGRAVINGS TO 
EARTHENWARE. 

Antiquity of Enamel Coloring. — Specimens from Ancient Egypt. — 
From the Royal Works at Sevres. — Painted Ware of Worcester. — 
Of Staffordshire. — Of Derby. — Of Yorkshire. — Great Services of Mr. 
Wedgwood in this Branch of the Manufacture. — Mystery observed 
in the Preparation of Colors. — Publication of Processes by M. Brong- 
niart. — Metallic Oxides. — Addition of fluxing Bodies necessary — And 
why. — Colors employed for tender and hard Porcelain. — Vehicle 
used with the Color. — Mode of their Combination. — Description of 
Colors. — Purple and Violet. — Red — Yellow — Blue — Green — Brown 
— Black — White. — Compound Colors. — Precautions necessary in 
forming those Compounds. — Gilding. — Lustre Ware. — Preparation of 
Colors. — Enamelling Kilns. — Trial Pieces. — Method of Gilding and 
Burnishing. — Copper-plate Engravings. — Mode of transferring Im- 
pressions to Earthenwares. — How performed in France 68 

CHAP. VII. 

ON THE MANUFACTURE OF TOBACCO PIPES. 

This Manufacture prosecuted to a great Extent. — Description of Ma- 
terial. — Rolling. — Boring. — Moulding.-— Polishing. — Baking. — De- 
scription of Kiln. — Of Crucibles. — Manufacture in Holland. — Origin- 
ally conveyed there from England .86 

CHAP. VIII. 

ON THE PORCELAIN MANUFACTURE OF CHINA. 

Obscurity wherein its Origin is shrouded. — Chiefly practised at King- 
te-ching. — Supposed Superiority of old China Ware. — Materials em- 
ployed. — Koa-lin. — Pe-tun-tse. — Their Preparation. — Oils or Varnish- 
es. — Their Composition. — Hao-che. — Its Superiority to Kao-lin. — 
Analysis of Kao-lin. — Extent of Factories at King-te-ching. — Great 
Number of Workmen employed. — Preparation of Materials. — Method 
of fashioning Utensils. — Moulds. — Division of Labor. — Deficiency of 
Chinese in the Art of Design.— Their excellent Colors. — Numerous 
Hands employed in decorating each Piece. — Bad Effect of this Sys- 
tem. — Blue long the only Color used for painting China Ware. — 



CONTENTS. 

Mode of preparing various Colors. — Chinese ignorant of Chemical 
Science. — Umiam. — Tsou-Tchi. — Kia-tsing. — Method of forming it. 
— Chinese Furnaces. — Passion for old Porcelain. — Ku-tong. — Mock 
Antiques. — Reasons for Costliness of China Ware in Europe. — High 
Prices formerly paid in China.— Finest Specimens not brought to 
Europe. — Porcelain Tower at Nan-King. — Chinese Potters prepare 
Materials for the Use of their Descendants. — Common Wares made 
in China. — Attempt of the Emperor to transfer the Manufacture to 
Pekin. — His want of Success 90 



PART II. 
GLASS MANUFACTURE. 

CHAPTER I. 

ON THE NATURE AND PROPERTIES OF GLASS. THE HISTORY OF 

ITS INVENTION, AND MANUFACTURE. 

Nature of Glass. — Its various Properties. — Its Utility to all Classes. — 
The Assistance it lends to Science. — Admiration of the Ancients. — 
Excessive Prices formerly paid. — Origin of its English Name. — Aris- 
totle's Problems. — First invention ascribed to the Phoenicians. — Glass 
known to the Ancient Egyptians. — Manufactories of Alexandria. — 
Utensils found in Herculaneum. — Urns in British Museum. — Mal- 
leable Glass. — Tax on Glass, by Alexander Severus. — Portland Vase. 
— Glass employed in forming Windows. — Not much used in Eng- 
land till the Eleventh Century. — Privileges granted to Manufactur- 
ers in France. — Plate Glass casting. — Establishment at St. Gobain. — 
Its early Failure — And Revival. — Manufacture commenced in Eng- 
land.— Of Flint Glass.— Of Plate Glass.— Establishment of British 
Cast Plate Glass Company. — Chinese unacquainted with Glass-mak- 
ing. — Importance of the Manufacture in England. — Glass made a 
Source of Revenue. — Bad Effect upon Consumption. — Increase of 
Duty. — Consequent Decrease of Manufacture. — Diminution of Duty 
on Plate Glass. — Increase of Quantity made 105 

CHAP. II. 

ON THE VARIOUS INGREDIENTS EMPLOYED IN MAKING GLASS. 

Glass always composed of Silex with Alkali. — Different Descriptions 
of Glass.— Sea Sand.— Soda and Potash.— Pearlash.— Barilla.— Kelp. 
— Wood-ashes. — Nitre. — Litharge. — Minium. — Manganese.— Arsen- 
ic— Borax.— Chalk 119 



CONTENTS. XI 

CHAP. III. 

ON THE CONSTRUCTION OF FURNACES, ETC. 

Stability of Furnace essential. — Fritting Furnace, or Calcar. — Its Use. 
—Working Furnace.— Double Furnace. — Proportionate Dimensions 
of Furnace and Pots. — Wood Furnaces. — Comparative Consumption 
of Fuel in Wood and Coal Furnaces. — Annealing Oven. — LierPans. 
— Glass Pots. — Their Formation and Seasoning 125 

CHAP IV. 

ON THE MANUFACTURE OF FLINT GLASS. 

The most beautiful and costly Kind of Glass. — Importance of its Qual- 
ity for Optical Purposes. — Experiments for its Improvement. — Under- 
taken by the Royal Society. — Promoted by Government. — Distin- 
guishing Properties of Flint Glass. — To what owing. — Different Com- 
positions. — Process of Melting. — Glass-gall. — Its Use. — Curious Phe- 
nomenon. — Implements. — Collecting Glass on Rod. — Marver. — Parai- 
son. — Blowing. — Reheating. — Elongating. — Pontil. — Fashioning.— 
Detaching. — Removal to Annealing Oven. — Moulding. — Annealing. 
—Why indispensable. — Bologna Phials. — Rupert's Drops 131 

CHAP. V. 

ON THE MANUFACTURE OF CROWN GLASS, BROAD GLASS, AND 
BOTTLE GLASS. 

Description of Crown Glass. — Harder than Flint Glass. — More difficult 
to fashion. — Its Composition. — In France. — In England. — Fritting. — 
Cullet. — Refining. — Sulphate of Soda. — Vegetable Charcoal. — Gath- 
ering — Blowing — Reheating — Flattening. — Transferring to Pontil. — 
Twirling. — Expanding. — Opening. — Annealing. — Nice Regulation of 
Temperature required in this Process. — Qualities of Crown Glass. — 
German Glass. — Broad Glass. — Inferior to Crown Glass. — Its Compo- 
sition. — Preparation. — Working. — Bursting. — Opening. — Annealing. 
— Bottle Glass. — Manufacture checked by Increase of Duty. — Com- 
position. — Restrictions as to Materials. — Their bad Tendency. — Supe- 
riority of Bottle Glass for certain Purposes. — Materials employed in 
France. — At Newcastle. — Fashioning. — Moulding. — Experiments 
suggested by Count Chaptal. — Klingstein. — Volcanic Granite 143 

CHAP. VI. 

ON THE MANUFACTURE OF PLATE GLASS. 

Different Descriptions of Plate Glass. — Blown Plates limited in Size. — 
Cast Plate Works at Ravenhead. — Difficulties of the Process. — Ma- 
terials. — Various Compositions. — Borax. — Mixing Materials. — Frit- 



Xll CONTENTS. 

ting. — Furnaces and Crucibles at St. Gobain. — Potts. — Cuvettes. — 
Regulation of Firing. — Casting Tables. — Arrangements of Foundery 
at Ravenhead. — Annealing Ovens. — Process of Casting Plates. — 
Annealing. — Squaring. — Grinding. — Economical Improvement. — 
Smoothing. — Emery Powder. — Comparative Value of large and small 
Plates. — Polishing. — Silvering. — Preparation of Amalgam. — Mode 
of its Application. — Blowing Plate Glass. — Punching. — Partial Cut- 
ting. — Transfer to Pontil. — Completion of Cutting. — Opening. — An- 
nealing. — Sizes of Plates. — Effect of Sun's Rays in discoloring Plate 
Glass 154 



CHAP. VII. 

ON THE COMPOSITION OF ARTIFICIAL GEMS. 

Great Interest formerly attached to this Subject. — Different Composi- 
tions for artificial Gems. — Mode of Preparation. — Rock Crystal for- 
merly employed. — Not superior to Sand. — Diamond Pastes. — Selec- 
tion of various Pastes for imitating different Gems. — Reasons for 
such Selection 171 

CHAP. VIII. 

ON THE MANUFACTURE OF GLASS FROM CALCINED BONES. 

Preparation of Bones. — Their Vitrification. — Process known to Becher. 
— Concealed by him. — Curious Suggestion as to its Employment. — 
This Glass highly electric when newly made 175 

CHAP. IX. 

ON THE USE MADE OF THE BLOWPIPE, AND ON VARIOUS SMALL 

MANUFACTURES OF GLASS. 

Thermometer Tubes. — Manner of giving to them an elliptical Bore. — 
Blowpipe and Apparatus described. — Materials used. — Method of 
working. — Sealing Tubes. — Bending and Joining Tubes. — Bulbs. — 
Spun Glass. — Watch Glasses. — Lunette Glasses. — Glass Beads. — 
Manufactory at Murano. — Striped Tubes. — Mode of forming Beads. 
— Sorting them. — Numerous Kinds of Beads. — Mock Pearls. — Man- 
ner of their Invention — And Formation. — Dial Plates. — How form- 
ed. — Lettering and Figuring 176 

CHAP. X. 

ON THE FORMATION OF LENSES. 

Preparation of the necessary Tools. — Choice of Glass. — Grinding. — Pol- 
ishing, — Curdled Lenses. — Means used for avoiding this Defect.. . 189 



CONTENTS. Xlil 

CHAP. XI. 

ON THE PRINCIPAL DEFECTS OBSERVABLE IN GLASS. 

Striae. — Render Glass unfit for Optical Purposes. — Threads. — Render 
Glass fragile. — Cause of this. — Tears. — One of the greatest Defects. 
— Render Glass useless. — Knots. — Bubbles. — Whence they proceed. 
—Do not much affect the Quality of Glass. — Objects to be attained 
for avoiding these Defects. — M. Guinand. — His humble Origin. — En- 
ergy of Character. — Examines Telescopes and constructs others. — 
Unable to procure Glass of good Quality. — Is incited to examine into 
the Causes of Inferiority. — His extraordinary Perseverance amidst 
Accidents and Difficulties. — His ultimate Success. — Accident lead- 
ing to further Improvement. — Prosecutes his Art in Bavaria. — Re- 
turns to Switzerland, and further pursues his favorite Object. — Dies. 
— Frauenhofer. — Rises from Obscurity by his Talents. — His Scientific 
Acquirements. — Produces Specimens of perfect Glass. — Dies at an 
early Age. — Respect paid to his Memory 192 

CHAP. XII. 

ON THE SPECIFIC GRAVITY OF GLASS. 

Importance of this Quality.— Experiments of Loysel. — His Reasoning 
and Formulae. — Specific Weight augmented by Lime. — Mixed Glass- 
es. — Their specific Weight. — Method of determining this. — Influ- 
ence of Temperature on the specific Weight of Glass 202 

CHAPTER XIII. 

ON THE ART OF COLORING GLASS. 

Antiquity of this Art. — Specimens of Roman Mosaic. — Analysis of these 
by Klaproth. — Metallic Oxides. — Gold Purple. — Its great coloring 
Power. — Kunckel. — His Proficiency in coloring Glass. — Yellow Col- 
or. — From Silver. — From Lead. — From Tartar. — From Beech Wood 
Charcoal. — From Oxide of Iron. — Green. — Black Glass. — Blue. — Di- 
rections found in old Authors. — Imitation of the Garnet. — Of the 
Amethyst. — Of the Emerald.— Of Sapphires. — Opaque Glasses. — 
Black. — White. — Opal. — Ancient Pictures formed of colored Glass. — 
How executed. — Description of Ancient Mosaics. — Most recent Pro- 
secution of this Art. — Accidental coloring of Plate Glass at St. Go- 
bain. — Ineffectual Attempts to reproduce this Effect 208 

CHAP. XIV. 

ON THE ART OF STAINING AND PAINTING GLASS. 

This Art more recent than that of coloring. — Encouraged by the Monks. 
— Early Specimen at St. Denis. — Art never much cultivated in Eng- 
B 



XIV CONTENTS. 

land. — Splendid Paintings at Gouda. — Directions given by old Au- 
thors for composing Colors. — Fluxes. — Vehicles for diluting Colors. — 
Description of various Stains. — Method of floating these.— Of Paint- 
ing on Glass. — Imitation of Ground Glass with transparent Patterns. 
— Description of Kiln employed. — Method of Firing. — Second and 
third Firing. — Ancient Method of fixing different-colored Glasses on 
each other 223 



CHAP. XV. 

ON THE ART OF CUTTING, ENGRAVING, AND ETCHING ON GLASS. 

Origin of the Art of cutting Glass. — Implements. — Manner of their Em- 
ployment. — Frosting. — Patterns produced by Moulding. — Engraving 
on Glass. — Executed with the Diamond. — Etching. — Schwanhard. — 
Difference of his Practice from that now used. — Method of Etching. 
— Fluoric Acid. — Glass Incrustations. — Origin of the Art. — Improve- 
ments therein 235 

CHAP. XVI. 
ON THE DEVITRIFICATION OF GLASS. 

First observed by Neumann. — Experiments of Reaumur. — Substance 
known as Reaumur's Porcelain. — Inappropriateness of this Name. — 
Uses to which the Substance may be applied. — Common Bottle Glass 
most proper for this Conversion. — Method of effecting the Change. — 
Produced solely by Heat. — Experiment of Dr. Lewis. — Revivifica- 
tion. — Experiments of Sir James Hall. — Proposal suggested thereby. 
—Observations of Guyton-Morveau. — Artificial Intaglios. — Mock 
Onyxes. — Power of devitrified Glass to bear sudden Changes of Tem- 
perature. — Experiments with colored Glass. — Glass devitrified by 
burning Lava. — The Process promoted by multiplying the Ingredi- 
ents of Glass. — Devitrified Glass conducts Heat more perfectly than 
when vitreous. — Becomes a Conductor of Electricity. — Retains this 
Property when revitrified .243 



MANUFACTURE 

OF 

PORCELAIN. 



A 

TREATISE 

ON THE 

PROGRESSIVE IMPROVEMENT AND PRESENT STATE 

OF THE 

MANUFACTURE 

OF 

PORCELAIN. 



CHAPTER I. 

HISTORICAL NOTICES OF THE MANUFACTURE. 

Origin of the Art.— Brickmaking— Potter's Wheel.— Indian Earthenwares. 
— Roman Water-Pipes. — Remains of Ancient Pottery. — Roman Potteries 
in Staffordshire.— Antiquity of the Art in the East.— Porcelain first 
brought to Rome. — Figures found with Egyptian Mummies. — Chiria- 
Wares brought by Portuguese Traders. — Discovery by De Botticher in 
"Saxony. — Manufacture attempted in France. — Investigations of Reau- 
mur. — Jonas Hanway's Account of Collection at Dresden. — Works at 
Berlin. — English Potteries. — Plot's Account. — Improvements in Glazing. 
—White Stone-Ware.— Wedgwood's Improvements.— Exportations by 
Wedgwood. — His Inventions. — Characteristics of True Porcelain. — Porce- 
lain of Derby.— Of Coalport.— Of Worcester. — Of Rotherham. 

The formation of earthen vessels capable of containing fluid 
substances is an art of the very highest antiquity. In the 
rudest stages of society, the want of such vessels would call 
forth the inventive powers of mankind ; and, probably, the 
hard shells of some vegetable productions, such as gourds and 
the larger descriptions of nuts, would be first adapted to the 
purpose. The pliant and infrangible nature of the skins of 
animals taken in the chase would, at a very early period, point 
them out as convenient recipients for fluids ; but the prepara- 
tion of these, as well as the fashioning and hollowing of 
wooden bowls, supposes a previous knowledge of some manual 
arts, and implies the possession of tools. After even these 
had been attained, and supposing that the existence of fire, 
and its use in preparing food, had become known, vessels 
formed of wood, or of the hides of animals, would be of little 
use in rendering that knowledge available. Some savage 
tribes thus circumstanced, have, indeed, made wooden bowls 
subservient to this purpose, by throwing into the fluids which 

B2 



18 PORCELAIN MANUFACTURE. CHAP. I. 

they contain, stones previously heated in the fire. This man- 
ner of boiling' water, and of cooking provisions, is, however, at 
best, but an inconvenient process, and would be immediately 
abandoned upon the discovery that certain earthern substances 
were endowed sufficiently with the quality of resisting the 
action of fire. 

It must continue matter of doubt, whether the fashioning 
and hardening of clay was practised first by the brickmaker or 
by the potter. We know that bricks, thoroughly burned, 
were used at the building of the tower of Babel, 2200 years 
before the commencement of the Christian era, and 600 years 
prior to the carrying away into captivity of the Israelites. 
That the use of bricks, for the purposes of building, must have 
become exceedingly common at this last-mentioned period, is 
evident, from the great numbers of the captive Jews who were 
compelled by their Egyptian task-masters to prosecute the 
manufacture. It appears that the bricks then made were not 
artificially burned ; the chopped straw which entered into 
their composition, and which served to hold the mass together, 
would, in such case, have been destroyed. Specimens of very 
ancient Egyptian bricks, which have been brought to this 
country, confirm the supposition that the heat of the sun was 
alone employed in baking them. 

Many centuries later, the Romans conducted the manufac- 
ture of bricks with a great degree of perfection. A compari- 
son of very ancient Roman ruins, with buildings of modern 
elevation, will show at once how superior are the bricks em- 
ployed in the former, both as regards solidity and beauty. 
Specimens of the potter's art, if even any such existed at an 
equally early period, could not be expected to continue in be- 
ing for so many ages ; if, indeed, they had withstood the de- 
stroying hand of time, and descended to the present day, they 
would not bring with them any direct testimony of their date 
of production, and could throw little or no light upon the ques- 
tion of priority. It is certain, however, that, in very remote 
ages, the potter's art had attained to a considerable degree of 
usefulness, since the earliest authentic records allude to the 
potter's wheel as to an implement of then high antiquity. 

The same wants would arise in different portions of the 
globe ; and in all cases, where similar means for their grati- 
fication presented themselves, it is not surprising that these 
means should be equally embraced by all. Accordingly, it 
has been found, in newly-discovered countries, and among 
people comparatively rude and unacquainted with most of the 
arts which conduce to human convenience, that the use of 
earthen vessels has been enjoyed for ages before the existence 



CHAP. I. HISTORICAL NOTICES. 19 

of the people was even surmised. Among other proofs of 
this fact, it may be mentioned, that vases have been found 
among the aboriginal Indians on the Mosquito shore, which, 
even by those people, were preserved as memorials of antiquity. 
There is no reason to doubt that these vessels were the man- 
ufacture of the country in which they were found, as the re- 
mains of ancient potteries have been discovered at a considera- 
ble distance up the Black River on that coast. 

There would be little advantage in entering upon an in- 
vestigation to determine the precise degree of antiquity of the 
potter's art, if even there existed any sufficient guides to direct 
us in the inquiry. It will be more profitable at once to fore- 
go all fanciful speculations, and to commence the relation of 
a few facts, and such only as bear the stamp of authenticity. 
The detail of these need not occupy much time or space, 
which may be more advantageously devoted to descriptions of 
the art as it exists in the present day, than to the building up 
of theories, the truth of which can never be demonstrated. 

We learn, on the authority of Vitruvius, who wrote in the 
Augustan age, that the Romans then made their water-pipes 
of potter's clay. This people, who introduced a knowledge of 
the useful arts practised by themselves wherever their con- 
quests were extended, established potteries in England, where, 
among other articles, similar water-pipes were made. Some 
of these, about a century ago, were dug up in Hyde Park. 
They were found to be two inches in thickness, and were 
firmly jointed together with common mortar mixed with oil. 

It has been asserted that the ancient Britons were in the 
practice of making pottery before the invasion of this country 
by the Romans ; and in support of this belief is brought the 
fact, that urns of earthenware have been taken from barrows 
in different parts of the kingdom. On the other hand, the 
concurring testimony of various writers gives reason for sup- 
posing that our ancestors were in those days supplied with 
such articles by the Venetians. Vestiges of considerable Ro- 
man potteries are discernible in many parts of the island, and 
particularly in Staffordshire, on the site of the great potteries 
which have so long been carried on in that county. In sink- 
ing pits for various purposes, remains of Roman potteries have 
occasionally been discovered there at a considerable depth 
below the surface. 

Governor Pownall relates, that in his time (1778) the men 
employed in fishing at the back of the Margate Sands, in the 
Queen's Channel, frequently drew up in their nets some 
coarse and rudely -formed earthen vessels, and that it was 
common to find such pans in the cottages of these fishermen. 



20 PORCELAIN MANUFACTURE. CHAP. I. 

It was for some time believed, that a Roman trading vessel, 
freighted with pottery, had been wrecked here ; but on more 
particularly examining the spot, called by the fishermen Pud- 
ding-pan Sand, some Roman bricks were also discovered, ce- 
mented together, so as to prove that they had formed part of 
some building. Further researches showed that, in Ptolemy's 
second book of Geography, an island was designated as existing 
in the immediate vicinity. Such pans as were recovered in a 
sound state were of coarse materials and rude workmanship — 
many having very neatly impressed upon them the name of At- 
tilianus ; but fragments of a finer and more fragile description 
of pottery were likewise brought to the surface ; and little doubt 
remains that, during the time of the Roman ascendency in 
England, a pottery was established here upon an island which 
has long since disappeared, and that the person whose name 
has been thus singularly preserved was engaged in its man- 
agement. 

The high antiquity of the art in China, and the proficiency 
which had been acquired in its pursuit, several centuries be- 
fore the produce of their manufactories found its way to Eu- 
rope, will be shown in a future chapter. Porcelain of superior 
quality was likewise made in Japan at an equally early period ; 
and we learn from Propertius, that at a very remote date, the 
art was commonly practised in Persia, the vessels manufac- 
tured there joining to all the excellencies possessed by the 
porcelain of China, the quality of resisting the action of fire 
to a degree which fitted them for being used in the prepara- 
tion of food. 

Most authors who have noticed in any way the state of 
commerce among the ancients, have referred to the Vasa 
Murrhina particularly described by Pliny,* and mentioned by 
various Greek and Roman authors. The general opinion was 
long in favor of these vases having been the true porcelain of 
China. This opinion has, however, been examined with con- 
siderable industry and erudition by M. l'abbe le Bland and M. 
Larcher, in two dissertations,! whereby it is rendered evident 
that the Vasa Murrhina were formed out of a transparent stone 
dug from the earth in some of the eastern provinces of Asia.J 
There is abundant evidence to show that Oriental porcelain 
was not uncommon in Europe during the first century. The 
pieces of this manufacture which, according to Pliny, were 
first seen in Rome, were brought there from Pontus in Asia, 
by the army of Pompey, 64 years before Christ. 

* Nat. Hist. lib. xxvii. | Mem. de Litterat. tome xliii. 

% Robertson's Disquis. concerning India, second edit. p. 387. 



CHAP. I. HISTORICAL NOTICES. 21 

Little figures covered with a fine deep-blue glaze, which 
are found deposited with Egyptian mummies, cause it to ap- 
pear that porcelain was made in Egypt in very ancient times. 
It is a curious fact, that the coloring matter wherewith these 
figures are ornamented, and which has been subjected to va- 
rious chemical tests, affords every indication of its being oxide 
of cobalt, the identical substance employed for the same pur- 
pose by the European porcelain manufacturers of our day, but 
the use of which was unknown to us until a comparatively 
recent period. The ore of cobalt was formerly thrown aside 
by the miners of Saxony as useless, or was employed only in 
mending roads.* 

The Portuguese traders were the means of introducing the 
fine earthenwares of China into more general use in Europe ; 
and the name assigned to the fabric, as distinguishing it from 
the coarser descriptions of pottery of domestic manufacture, 
was most probably given by them — -porcellana signifying, in 
the Portuguese language, a cup. It has been attempted to prove 
a different origin for the name — attributing this to the resem- 
blance which the glazing or varnish, and probably the colors, 
of porcelain bear to the shells used in some parts of the East 
instead of money (couries), and which, from the similarity of 
their shape to that of the back of a little pig, were also called 
porcella. 

The possession of porcelain vessels afforded but little insight 
into the nature of their composition or the mode of their man- 
ufacture, as to which many unfounded theories were from 
time to time proposed. It was long believed, on the authority 
of Cardan and the elder Scaliger — who, although violently 
opposed to each other on various and more important subjects, 
yet agreed in this — that porcelain was made from a mixture of 

* " About the end of the fifteenth century, cobalt appears to have been 
dug up in great quantity, in the mines on the borders of Saxony and Bohe- 
mia. As it was not known at first to what purpose it could be applied, it 
was thrown aside as a useless mineral. The miners had an aversion to it, 
not only because it gave them much fruitless labor, but because it often 
proved prejudicial to their health, by the arsenical particles with which it 
was combined ; and it appears even that the mineralogical name cobalt then 
first took its rise. Frisch derives it from the Bohemian word kow, which 
signifies metal ; but the conjecture that it was formed from cobalus, which 
was the name of a spirit that, according to the superstitious notions of 
the times, haunted mines, destroyed the labors of the miners, and often 
gave them a great deal of unnecessary trouble, is more probable. The 
miners perhaps gave this name to the mineral out of joke, because it 
thwarted them as much as the supposed spirit, by exciting false hopes and 
rendering their labor often fruitless. It was once customary to introduce 
into the church service a prayer, that God would preserve miners and their 
works from Kobolts and spirits."— Beckmann, Hist, of Inventions, vol. ii. 
pp. 341, 342. 



22 PORCELAIN MANUFACTURE. CHAP. I. 

broken egg and sea shells, which were preparatively buried in 
the earth for nearly a hundred years. 

It was not until the beginning of the 18th century that any 
light was thrown upon the subject. At that time, the Jesuit, 
Francis Xavier d'Entrecolles, who was residing as a missionary 
in China, contrived to elude the jealous vigilance so generally 
practised towards strangers in that country ; and not only ob- 
tained specimens of the earths used in the composition of their 
porcelain, but also acquired some knowledge of the processes 
employed in the manufacture at King-de-ching. A very cir- 
cumstantial letter was written by the learned father on the 
subject, and published by Grosier in his general description of 
China : but owing to a want of practical knowledge on the 
part of D'Entrecolles, his descriptions proved so defective in 
many particulars, as to afford little or no assistance ; besides 
which, it was not until some time after the publication of his 
letter that any substances similar to the earths transmitted by 
him could be discovered in France. 

About the same time, and while the acquisition of these 
Chinese specimens was exciting the celebrated Reaumur to 
their examination, and to the institution of a series of experi- 
ments which will be hereafter mentioned, an incidental dis- 
covery made by the baron de Botticher, a German alchemist, 
occasioned the establishment of the porcelain manufacture in 
Saxony. While prosecuting his vain experiments in search 
of the philosopher's stone, this man prepared some crucibles, 
which he observed were caused by the action of heat to assume 
all the characteristics of Oriental porcelain. Blinded by the 
avarice which prompted their visionary labors, the adepts of 
that day seem generally to have turned away from the im- 
portant discoveries that courted their notice, and which were 
thus reserved to reward the patient investigations of more phi- 
losophic minds in latter times. From this reproach De Botti- 
cher is free. The importance of the real discovery thus made 
was sufficiently apparent, and he had the wisdom to abandon 
immediately his former pursuit, and to give up the energies 
of his mind to the establishment of a manufacture, which was, 
in the end, productive of more beneficial results to himself and 
to his country, than if he had indeed been successful in his 
alchemical labors. The world at large, did not immediately 
reap the full benefit of this discovery, as, with a jealousy but 
too common, the processes used in the Dresden works were 
veiled in impenetrable secrecy. Up to the period of De Bot- 
ticher's death, in 1719, only white porcelain was made in 
Saxony; yet the success with which this manufacture was 
accompanied, occasioned attempts at imitation in France ; and 



CHAP. I. HISTORICAL NOTICES. 23 

porcelain works were established at St. Cloud, and in the 
Fauxbourg St. Antoine at Paris — the fabrics produced in which, 
although of beautiful external appearance, were wanting in 
most of the qualities essential to good porcelain. 

The investigations of Reaumur, already alluded to, were 
undertaken with more rational views, and prosecuted with a 
more liberal feeling. The result of his researches was com- 
municated by him to the Academy of Sciences, and published 
by that body in 1727 and 1729. Having procured specimens of 
Oriental, Saxon, and French porcelains, and broken them, he 
proceeded to examine their internal structure. The grain in 
both the Chinese and Saxon pieces appeared compact, smooth, 
and shining ; while that of the French ware was less close and 
fine, without lustre, and its grain resembled sugar. He next 
proceeded to ascertain their habitudes on exposure to great 
heat in a crucible, and reported, ' that all the European speci- 
mens were melted, while that of China remained unaltered. 
This most essential difference led Reaumur to discover the 
true nature of porcelain, which is a semi-vitrified compound, 
in which one portion remains infusible at the greatest heat to 
which it can be exposed, while the other portion vitrifies at 
that heat, and enveloping the infusible part, produces that 
smooth, compact, and shining texture, as well as transparency, 
which are distinctive of true porcelain. Macquer, in his 
Chemical Dictionary, asserts, that Reaumur was wrong in class- 
ing the Saxon manufacture with the other fusible porcelains 
of European production ; since the materials of which it is 
composed have always been similar to those of which the China 
ware is made, one portion being absolutely infusible during the 
baking. 

In his examination of the two porcelain earths received 
from China, which are called in that country pe-tun-tse and 
kao-lin, Reaumur made a small cake of each substance, sepa- 
rately, and exposed both to the heat of a porcelain furnace. 
One, the pe-tun-tse, was fused by this means, without any ad- 
dition ; while the other, kao-lin, gave no sign of fusion. He 
next intimately compounded the two earths, and found, when 
the mixture was baked, that it had acquired all the qualities 
of the finest Chinese ware. 

All that was then wanting for the perfect imitation of this 
admired production was the discovery of materials analogous 
to the specimen furnished by D'Entrecolles. The search for 
these was very speedily successful ; and the manufacture of 
porcelain having, from this time, been taken under the royal 
patronage in France, the works of Sevres produced specimens 



24 PORCELAIN MANUFACTURE. CHAP. I. 

of art which vied successfully with those of Dresden and 
China. 

Mr. Jonas Han way, in the account of his travels published 
in 1753, has given a detailed account of the immense collec- 
tion of porcelain deposited in the Chinese palace at Dresden. 

" The vaults of this palace," says Mr. Hanway, " consist of 
fourteen apartments filled with Chinese and Dresden porce- 
lain. One would imagine there was sufficient to stock a whole 
country ; and yet they say, with an air of importance, that a 
hundred thousand pieces more are wanted to complete the in- 
tention of furnishing this single palace. 

" Here are a great number of porcelain figures of wolves, 
bears, leopards, &c. — some of them as big as the life — a pro- 
digious variety of birds, and a curious collection of different 
flowers. A clock is preparing for the gallery, whose bells are 
to be also of porcelain : I heard one of them proved, and think 
they are sufficient to form any music ; but the hammers must 
be of wood. 

" Here are forty-eight large China vases, which appear to 
be of no use, nor any way extraordinary, except for their great 
size ; and yet his Polish majesty purchased them of the late 
king of Prussia at the price of a whole regiment of dragoons." 

One part of this collection must have been peculiarly in- 
teresting, as it exhibited, in an orderly arrangement, specimens 
of Dresden manufacture laid up by this king of Poland, from 
the first efforts of De Botticher, through every subsequent 
gradation; "an idea," says Mr. Parke, "truly philosophical, 
and which reflects more honor on his memory than the barter- 
ing away the liberties of his subjects for pieces of foreign 
porcelain." 

Frederick the Great, when he conquered Saxony, forcibly 
carried away several of the best workmen from the manufac- 
tory at Meissen, near Dresden, and conveyed them to Berlin, 
where, since that time, a considerable quantity of very good 
porcelain has been made for the private advantage of the mon- 
arch. As many as 500 men are constantly employed in this 
establishment ; but although much of their material is drawn 
from Saxony, the Prussian porcelain has never equalled in 
quality that of Dresden. 

It is generally believed, that since the time when they were 
first established by the Romans, potteries have always existed 
in Staffordshire, but it is certain that until the beginning of 
the eighteenth century the manufacture was confined to a 
few objects of the commonest and coarsest description. 

The district in this county wherein the great bulk of Eng- 
lish manufactured earthenware is produced, is situated about 



CHAP. I. HISTORICAL NOTICES. 25 

a mile from the borders of Cheshire. The potteries commence 
at a village called Golden Hill, and extend for a distance of 
more than seven miles, passing through other towns and vil- 
lages to Lane End. The names of the places comprised in 
this district, intermediate between the two already mentioned, 
are Newfield, Smithfield, Tunstall, Longport, Burslem, Co- 
bridge, Etruria, Hanley, Shelton, Stoke, Lower Lane, and 
Lower Delf. All these have formerly been sufficiently dis- 
tinct from each other ; but the increase of the staple manufac- 
ture of the district has called for the erection of so many new 
potteries and dwelling-houses, that their individuality has been 
lost, and to a stranger the whole presents very much the ap- 
pearance of one large town. In every part of the kingdom, 
except the district itself, the whole are ranked under one 
general name — that of the Potteries. Etruria is the creation 
of the celebrated Josiah Wedgwood, by whom the place was 
thus named after one of the ancient Italian states, celebrated 
for the tasteful forms it gave to its pottery, specimens of which 
have materially promoted the improvement of our modern 
English wares. 

In the year 1686, when Dr. Plot published a Natural His- 
tory of Staffordshire, its traffic in earthenware was very unim- 
portant — being carried on only by the workmen themselves, 
or by pedlars, who conveyed the pieces in baskets on their 
backs through the adjoining counties. Abqut the time just 
mentioned (1690), two brothers, named Elers, came from Nu- 
remberg, in Holland, and settled at Bradwell, where they 
made an improved kind of red ware, and introduced the art 
of glazing the vessels by throwing common salt into the oven 
at a certain period of the baking.* Every precaution was 
used by the brothers to keep their processes secret ; and it is 
probable that this circumstance, joined to the success of the 
strangers, excited the enmity and jealousy of their neighbors 
to the degree which obliged them to leave the country. The 
pretext assigned for this persecution was the alarm occasioned 
by the fumes from thei* kilns during the time of glazing. These 
fears subsided, however, when the process was continued by 
their successor. This man, whose name was Astbury, had, it 
is said, become master of their secrets by a singular stratagem. 
Feigning to be of weak intellect, and assuming an appropriate 
vacuity of countenance, he obtained employment in the Brad- 
well works, and submitted to all the drudgery and contumely 
which were drawn upon him by his supposed imbecility. By 

* The salt is decomposed by this means ; and, rising in fumes, the alkali 
which it contains combines with the silica of the ware, and forms a true 
glass which covers the entire surface. 

c 



26 PORCELAIN MANUFACTURE. CHAP. I. 

this course of proceeding 1 , he was enabled, unsuspected, to 
acquire a knowledge of all that was done in the manufactory, 
and to make models for his own use of all the utensils. 

The advantages of this method of glazing with salt were so 
apparent, that in a short time it was very generally adopted ; 
and on Saturday, the day appropriated to this process, the 
thick fumes from nearly sixty potteries filled the towns to a 
degree which darkened the atmosphere, and covered the hills 
of the surrounding district* 

To Astbury is generally ascribed the introduction of white 
stone-ware, by the adoption of calcined flints in its composition. 
The popular version of the origin of this improvement states, 
that " while travelling to London on horseback, in the year 
1720, Astbury had occasion, at Dunstable, to seek a remedy 
for a disorder in his horse's eyes ; when the ostler at the inn, 
by burning a flint, reduced it to a fine powder, which he blew 
into them. The potter, observing the beautiful white color 
of the flint after calcination, instantly conceived the use to 
which it might be applied in his art."f 

The merit of this man has been somewhat overlooked, 
while contemplating the greater claims to admiration possessed 
by his more philosophic successor in the course of improvement. 
That could have been no common mind, however, which led 
Astbury to the long-continued pursuit of his object, by means 
so humiliating ; and which also enabled him, on the occasion 
just related, to seize upon a fact thus accidentally presented, 
and which, although of high importance to his art, might have 
passed unheeded before the eyes of many a common-place 
manufacturer. 

The step thus made was of consequence in preparing the 
way for the far greater advances towards perfection, after- 
wards accomplished by Mr. Josiah Wedgwood. This extra- 
ordinary man owed none of his success to fortuitous circum- 
stances. Devoting his mind to patient investigations, and 
sparing neither pains nor expense in accomplishing his aims, 
he gathered round him talented artists fjom different countries, 
and drew upon the stores of science for aid in pursuing the ob- 
jects of his praiseworthy ambition. The early and signal 
prosperity whereby his efforts were attended, served only as a 
motive urging him forward to new exertions, and as the means 
for calling forth and encouraging talents in others, in a manner 
calculated to promote the welfare of his country. Previously 
to his time, the potteries of Staffordshire produced only inferior 
fabrics, flimsy as to their materials, and void of taste in their 

* Parke, Chem. Cat. p. 125. t Parke, Chem. Cat. p. 126. 



€HAP. I* HISTORICAL NOTICES. 27 

forms and ornaments — the best among them being only- 
wretched imitations of the grotesque and unmeaning scenes 
and figures portrayed on the porcelain of China. But such 
have been the effects resulting from the exertions and exam- 
ple of this one manufacturer, that the wares of that district 
are now not only brought into general use in this country, to 
the exclusion of all foreign goods, which had before been 
largely imported, but English pottery has since been sought 
for and celebrated throughout the civilized world, and adopted 
even in places where the art was previously prosecuted. An 
intelligent foreigner, M. Faujas de Saint Fond, writing on this 
subject, says, " its excellent workmanship, its solidity, the ad- 
vantage which it possesses of sustaining the action of fire, its 
fine glaze impenetrable to acids, the beauty and convenience 
of its form, and the cheapness of its price, have given rise to 
a commerce so active and so universal, that in travelling from 
Paris to Petersburgh, from Amsterdam to the further part of 
Sweden, and from Dunkirk to the extremity of the south of 
France, one is served at every inn upon English ware. 
Spain, Portugal, and Italy, are supplied with it ; and vessels 
are loaded with it for the East Indies, the West Indies, and 
the continent of America."* 

It is not among the least of Mr. Wedgwood*s merits, that 
he overcame the disadvantages of a defective education ; and, 
amid the calls of an incessantly active life, found time wherein 
to school his mind in all the discipline necessary for investiga- 
tions purely scientific. The ample fortune which he acquired 
was ever ready for promoting the spread of knowledge, en- 
couraging the efforts of genius, and lessening, as far as possi- 
ble, the sufferings of his fellow-creatures. His charities, pub- 
lic and private, and especially in his own district, were ex- 
emplary and consistent. He gave life to many objects of 
public utility. The Trent and Mersey canal was undertaken 
and accomplished through his influence ; and by the benefits 
it has produced to the district, and to its proprietors, has fully 
approved his wisdom in its promotion. 

The principal inventions of Mr. Wedgwood were — 1. His 
table ware ; the merits of which are, that it has a dense and 
durable body, and is covered with a brilliant glaze, capable of 
bearing uninjured sudden and great vicissitudes of heat and 
cold. This ware, as it was capable of being manufactured 
with ease and expedition, could be sold at a cheap rate, and 
would still yield a handsome profit to the inventor. Its va- 
rious qualities, so superior to any possessed by previous manu- 

* Travels in England and Scotland (English translation,) vol. i. p. 97- 



28 PORCELAIN MANUFACTURE. CHAP. I. 

factures of either domestic or foreign production, caused this 
ware to be taken into immediate and universal favor with the 
public. Among others, the queen bestowed upon it the tribute 
of her admiration and patronage ; commanded it to be called 
queerts ware — a name which it continues to bear to the pres- 
ent day ; and honored Mr. Wedgwood by appointing him her 
majesty's potter. 

2. A terra cotta, which could be made to resemble por- 
phyry? granite, Egyptian pebble, and other beautiful stones of 
the silicious or chrystalline order. 

3. Basaltes, or black ware. This was a black porcelainous 
biscuit, having nearly the same properties with the natural 
stone. It would emit sparks when struck with steel; was 
capable of taking a high polish ; resisted acids ; and would 
bear, without injury, a stronger degree of heat than even the 
natural basaltes. 

4. White porcelain biscuit. This ware had a smooth, wax- 
like appearance, and was possessed of all the properties ex- 
hibited by the preceding invention, differing from it only in 
regard to its color. 

5. Bamboo, or cane-colored porcelain biscuit, of the same 
nature as the preceding. 

6. Jasper. This was also a white porcelainous biscuit, of 
exquisite delicacy and beauty, having in general all the prop- 
erties of the basaltes, with this in addition, — that it would re- 
ceive through its whole substance, from the admixture of 
metallic oxides, the same colors as those oxides communi- 
cate to glass or enamel in fusion. This peculiar property, 
which it shares with no other porcelain or earthenware body 
of either ancient or modern composition, renders it applicable 
in a very pleasing manner to the production of cameos, por- 
traits, and all subjects that require to be shown in bas-relief; 
since the ground can be made of any color that may be pre- 
ferred ; while the raised figures are of the purest white. 

7. A porcelain biscuit, possessing several properties that 
render it invaluable to the chemist, and which have occasioned 
this invention to be brought into general use in all laboratories. 
The ware is exceedingly hard, being little inferior in this re- 
pect to agate, whence it is peculiarly adapted for forming 
mortars. It resists the action of the strongest acids and of all 
corrosive substances, and has the further quality of being per- 
fectly impenetrable by any known liquid. 

The investigations of Reaumur, already detailed, make it 
evident that the characteristics of porcelain, as far as they de- 
pend upon semi- vitrification, may be obtained when ingre- 
dients wholly fusible are employed, provided the fire be care- 



Chap. i. historical notices. 29 

fully withdrawn from the oven at the precise moment when 
vitrification has arrived at, and not proceeded beyond, a certain 
point. Accordingly, this porcelain was, at one time, very com- 
monly produced both in this and other countries. The quality 
of goods thus composed is always inferior to that of true porce- 
lain ; and, if further or again exposed to the heat of the fur- 
nace, the substance would entirely change its nature, and run 
into a vitreous and shapeless mass. 

Porcelain of this description, much esteemed for its beauty, 
was long manufactured at Bow and at Chelsea. It was not 
until the year 1768, that Mr. Cookworthy discovered certain 
mineral substances in Cornwall similar in their properties to 
the porcelain earths of China ; and having secured to himself, 
by patent, the exclusive right of using those materials, was the 
first person who made true porcelain in England. 

In practising this art, Mr. Cookworthy, and those to whom 
he afterwards assigned his patent right, attained to considerable 
success as regarded the quality of their manufactures, although 
the demand for their goods did not prove proportionate to the 
money expended in bringing the processes to perfection. One 
probable cause for the inadequacy of their remuneration, ex- 
isted in the successful efforts of Mr. Wedgwood, which have 
been already detailed, for improving the quality of common 
earthenwares made in Staffordshire, whereby foreign porcelain 
was rendered less an object of desire, and consequently its suc- 
cessful imitation was no longer considered as being of any 
great importance. 

The extent to which, in the year 1785, this manufacture had 
arrived, and its importance to the three great interests of the 
country — landed, maritime, and commercial — may be collected 
from the evidence then given by Mr. Wedgwood before a com- 
mittee of the privy-council, and at the bars of the two houses 
of parliament. The question at that time under the considera- 
tion of the legislature, and upon which these examinations 
were taken, arose out of the proposal of government to abolish 
the system of commercial restrictions and disabilities then ex- 
isting between Great Britain and Ireland, and to render the 
intercourse between the two divisions of the empire nearly as 
free and unrestricted as that between the counties of Durham 
and Northumberland; a proposition so perfectly natural and 
reasonable in itself, that, but for the possession of records 
wherein they have been preserved, we might really be at a 
loss to conjecture the nature of the arguments whereby it was 
opposed and defeated. 

In the course of the discussions to which this subject gave 
rise in the house of lords, the marquess of Lansdowne, remark- 

C2 



30 PORCELAIN MANUFACTURE. CHAP. I. 

ing upon the evidence given by the respectable merchants and 
manufacturers at the bar of the house, declared that the result 
to which he in his own mind had arrived was the very opposite 
to the conviction which they had adopted. " Though much 
valuable information may," said his lordship, " doubtless, be de- 
rived from their evidence, it must not be forgotten that they are 
men peculiarly subject to prejudice and error, in all cases 
where their personal interests are concerned. Were any one, 
for instance, to ask a manufacturer of Halifax, what is the 
greatest crime upon earth ] Is it felony, is it murder, is it par- 
ricide 1 No ! he would answer ; it is none of these — it is the 
exporting of wool." 

In later times, we have seen this measure of justice and 
sound policy more successfully brought forward ; and it is ac- 
knowledged that each country has since been reaping benefits 
in consequence, upon the inevitable arrival of which nothing 
but the strongest commercial prejudices and national jealousy 
could have thrown even a momentary doubt. 

Mr. Wedgwood, in the course of the evidence already al- 
luded to, thus remarks : — " Though the manufacturing part 
alone in the Potteries, and their immediate vicinity, gives bread 
to 15 or 20,000 people, yet this is but a small object when com- 
pared with the many others which depend on it ; namely, 1st, 
The immense quantity of inland carriage it creates throughout 
the kingdom, both for its raw materials and finished goods. 
2d, The great number of people employed in the extensive 
collieries for its use. 3d, The still greater number employed 
in raising and preparing its raw materials in several distant 
parts of England, from near the Land's End, in Cornwall — one 
way along different parts of the coast, to Falmouth, Teignmouth, 
Exeter, Pool, Gravesend, and the Norfolk coast; the other 
way to Biddeford, Wales, and the Irish coast. 4th, The coast- 
ing vessels, which, after having been employed at the proper 
season in the Newfoundland fishery, carry these materials 
coastwise to Liverpool and Hull, to the amount of more than 
20,000 tons yearly ; and at times when, without this employ- 
ment, they would be laid up idle in harbor. 5th, The further 
conveyance of these materials from those ports, by river and 
canal navigation, to the Potteries, situated in one of the most 
inland parts of this kingdom ; and, 6th, The reconveyance of 
the finished goods to the different parts of this island, where 
they are shipped for every foreign market that is open to the 
earthenwares of England." 

Mr. Wedgwood very justly observed further, that this manu- 
facture is attended with some circumstances of advantage 
which are almost peculiar to itself; viz. that the value of the 



CHAP. I. HISTORICAL NOTICES. 31 

finished goods consists almost wholly in the labor bestowed 
upon them ; that every ton of raw materials produces several 
tons of merchandise for shipping, the freight being paid, not - 
upon the weight, but according to the bulk ; that scarcely a 
vessel leaves any of our ports whose lading is not in part made 
up of these cheap, bulky, and, for these reasons, valuable articles, 
to this maritime country ; and that fully five parts in six of the 
aggregate manufactures of the Potteries are exported to foreign 
markets. 

Important as were the advances which at that time had been 
made in the art, Mr. Wedgwood was still of opinion that they 
could be considered but as the beginning of improvements, — 
that these were still but in their infancy, and but of little mo- 
ment when compared with those to which the art was capable 
of attaining, through the continued industry and growing in- 
telligence of the manufacturers, in combination with and fostered 
by the natural facilities and political advantages enjoyed by the 
country; an opinion fully borne out by the event, and which 
our progressive experience shows to have been founded on clear 
and accurate perceptions. 

The manufacture of earthenwares in England is far from 
being restricted to the district in Staffordshire which has been 
described already as having acquired the name of " the Pot- 
teries." Establishments for making the commoner kinds of 
wares are to be found in many and various parts of the king- 
dom ; at Lambeth, especially, several manufactories of stone 
pottery have been carried on for considerably more than a cen- 
tury, producing articles which have never been surpassed in 
any country, either for the excellence of their materials and 
workmanship, or for the magnitude of the vessels and the va- 
riety of uses to which they are adapted. The Lambeth ware 
may, in fact, be pronounced perfect of its kind. 

Porcelain has long been made at Derby, and at Coalport, 
near Colebrook Dale, in Shropshire. Establishments have sub- 
sequently risen in the city of Worcester, wherein very beauti- 
ful specimens are produced ; and yet more recently, the 
manufacture of excellent porcelain has been engrafted upon a 
long-established pottery for commoner wares, situated at Swin- 
ton, near Rotherham, in Yorkshire. At the Rockingham 
works, which have been so named in compliment to their early 
patron, the celebrated marquess of Rockingham, porcelain is 
now produced which vies successfully in every kind of excel- 
lence with that of older English establishments. Among many 
other specimens which attest the proficiency of the Yorkshire 
manufacturers, two may be more particularly mentioned, which 
are deserving of more than common attention as denoting the 



32 PORCELAIN MANUFACTURE. CHAP. I. 

degree of advancement to which the art has reached in 
England. 

One of these pieces is a copy in enamel colors, made on a 
porcelain tablet, from an original painting by Vandyke, and 
now in the possession of the noble inhabitant of Wentwofth 
Castle. The subject of the picture is, " The earl of Strafford 
occupied in dictating his defence to his secretary." The exe- 
cution of this copy does justice to the masterly original ; and, 
in regard to expression and coloring, has been pronounced equal 
to the most admired productions of the Sevres works. The 
other specimen is remarkable not only for elegance of design, 
and the goodness of the workmanship, but also because it is 
believed to be the largest piece of porcelain that has hitherto 
been made in this country. It is a scent-jar, forty-four inches 
high, made and fired in one entire piece. The base, or plinth, 
is triangular, having a circular projection at each angle ; from 
these rise lions' paws, upon which the globular body of the jar 
is supported. The scent is allowed to escape through hexag- 
onal openings in the neck. The jar is divided into three com- 
partments, by as many rustic .handles of knotted oak ; while 
branches of the same tree, with their rich foliage rising from 
the plinth, are spread tastefully over the lions' paws, and thence 
entwining with the handles, rise and encircle the base of the 
neck. The ornaments of the cover are in keeping with those 
of the jar, it being covered with branches and foliage of the 
oak : the whole is surmounted by the figure of a rhinoceros. 
The three compartments into which the jar is divided are en- 
riched with highly finished paintings in enamel colors, executed 
by one of the proprietors of the works, from designs by Stothard, 
the subjects of which are drawn from the admirable romance 
of Cervantes. The circular projections at the base, and the 
cover, are adorned with paintings from nature, of six subjects 
of rare botanical plants, the originals of which are in the con- 
servatories of Wentworth Castle. The whole is relieved and 
enlivened by ornamental work, in burnished and chased gold ; 
and the work, both in its design and execution, is highly honor- 
able to the artists. 

Up to a comparatively recent period, the manufacture of 
earthenwares formed one of the very few branches of domestic 
industry which were left free from the evil effects of direct 
taxation, and, except in one branchy of very minor importance, 
the art is still in the enjoyment of this immunity ; to which fa- 
vorable circumstance may be imputed much of the signal and 
uniform success whereby it has been attended. In the year 
1812, when the duty upon glass bottles was doubled, the manu- 
facturers of these represented to the chancellor of the ex- 



CHAP. I. HISTORICAL NOTICES. 88 

chequer, that unless a countervailing tax was levied upon 
bottles, the latter, being wholly unburthened, would posses 
unfair advantage, and might be sold at prices that would di 
glass bottles out of use. This was a line of argument in i 
wise unpalatable to the minister, who readily caught at tth 
suggestion of a new object for taxation ; and a duty of five 
shillings on each hundredweight was immediately imposed upon 
all stone bottles the content of which should be two quarts and 
under. 

The levying of this duty calls for the attendance of revenue 
officers at all hours on the premises of every stoneware manu- 
facturer throughout the kingdom ; and it is very much to be 
doubted whether, in any one year since its first imposition, the 
expenses of collection have not more than absorbed the whole 
amount paid by the potters. The total quantity of stoneware 
made which is chargeable with the duty does not exceed 600 
tons annually, and a large proportion of this is used for purposes 
to which glass has never been applied. It is not very likely 
that stoneware, the utility of which for many purposes is ex- 
ceedingly great, would ever have been brought into competi- 
tion with a material so much lighter, and in many respects so 
much more convenient, even had the pottery continued free 
from the domiciliary visits of the exciseman ; and now that the 
experiment has been fairly tried during nearly twenty years, 
and has been found unproductive of any real revenue, there 
can be no sufficient reason for continuing the impost. 



CHAP. II. 



GENERAL DESCRIPTION OF INGREDIENTS USED IN THE MANU- 
FACTURE. 

Different branches of the art. — Ingredients used. — Properties of Alumina. — 
Its infusibility. — Contraction when exposed to heat. — Wedgwood's Pryom- 
eter. — Composition of Gems. — Great abundance of Clay. — Properties of Si- 
lica. — Its great abundance. — Sea sand. — Incapable of artificial solution in 
water. — Dissolvednaturally. — Springs at Carlsbad. — Boiling fountain in 
Iceland.— Fusion of Silex — Kinds of Clay used in Potteries.— Their vari- 
ous merits. — China clay of Cornwall. — Mode of its preparation. — Its anal- 
ysis. — Cornish Felspar. — Its fusibility.— Steatile.— Earth of Baudissero. — 
Its analysis. — Cornish sopestone.— Spuma maris. — Its employment in por- 
celain works in Spain. 

The art of manufacturing pottery and porcelain naturally 
divides itself into four different and distinct branches : the first 
of these comprehends a knowledge of the nature and peculiar 
properties of the various materials, whereof the vessels are 
composed ; the second comprises the methods used in combining 
these materials, and in fashioning the vessels ; the third branch 



34 PORCELAIN MANUFACTURE. CHAP. II. 

includes the choice and management of the colors and enamels 
employed in painting 1 and ornamenting the wares, together with 
the operations necessary for their conversion ; and the last di- 
vision embraces the means required for completing the manu- 
facture by the aid of fire. In describing, however, the different 
stages of the manufacture as they occur, the painting and baking 
processes must unavoidably be intermingled. 

The chief ingredients employed in the composition of all kinds 
of pottery are clay and flint: these are both classed by chemists 
among the primitive earths. The first of them, in its state of 
purity, is denominated alumina, or oxide of aluminum; and the 
latter is called silica, or oxide of silicium. It is only since the 
year 1754 that alumina has been acknowledged as a peculiar 
substance ; and the period is much more recent when the re- 
searches of Davy proved it to belong to the class of metallic 
oxides. 

It is of great importance to make choice of a suitable kind of 
clay for the manufacture ; but, according to the remark of the 
celebrated Vauquelin, it is much more important to combine 
this with a due proportion of flint, as good pottery differs from 
that which is inferior less in the original quality of its elements 
than in their proportions. 

Clay is an opaque and non-crystallized body, of dull fracture, 
soft enough in all states to take a mark from iron; when 
breathed on it exhales an odor which, from its peculiarity, takes 
its name from the material, and is termed argillaceous. This 
is owing to the oxide of iron which is mixed with it, as clay, 
when absolutely pure, does not emit any odor. Clay forms with 
water a plastic paste, having considerable tenacity, and which, 
by the action of heat, is brought to a very great degree of hard- 
ness : it is compact, smooth, and almost unctuous to the touch, 
and when dry, may be easily polished by the finger. It is not 
soluble in water, but mixes readily with it in all proportions, 
parting with difficulty from the last portion of that which it has 
absorbed : it will adhere to the tongue. The description of clay 
employed by potters is infusible in the heat of a porcelain fur- 
nace, where some kinds, owing to their being combined with 
oxide of iron, assume a red color, while others become of a pure 
white. The highest temperature to which clay can be exposed 
tends only to increase its density, hardening its substance and 
diminishing its volume. This diminution of volume produced 
by increased temperature is an apparent deviation from the 
general law of expansion by heat ; but the deviation is only ap- 
parent, and is probably produced by the vaporization of liquid, 
combined with the clay. Mr. Wedgwood found that the dimi- 
nution of volume produced by exposing the clay to these ex- 



chap. ii. wedgwood's pyrometer. 35 

treme temperatures, continued the same after the clay was suf- 
fered to cool, and therefore that its amount admitted of delib- 
erate and accurate measurement. He also supposed (though er- 
roneously) that the shrinkage of the clay was always propor- 
tional to the temperature to which it had been exposed. This 
led to his well-known invention of the pyrometer, an instru- 
ment for measuring degrees of temperature beyond the range 
of the common thermometer. The instrument consisted of 
small cylinders, composed of two parts of the porcelain clay of 
Cornwall, and one part of pure alumina. These, when baked 
in a low red heat and then cooled, were constructed of such a 
size as just to enter between the wider extremities of two 
brass rods, fixed on a plate twenty-four inches long, half an 
inch asunder at one end, and three-tenths of an inch at the 
other. These rods were divided to tenths of an inch, and con- 
sequently each division formed the 240th part of the whole 
length. The clay cylinders, being exposed to the heat which 
was required to be determined, were subsequently inserted be- 
tween these bars, and by reason of their contraction they ad- 
vanced between them to a point depending on the amount of 
their shrinkage. 

This pyrometer, however, has been found to be subject to a 
fatal defect. The shrinkage of the clay does not depend on 
the temperature alone of the fire to which it is exposed, but 
also on the length of time which the fire has acted upon it. 
Thus a lesser degree of heat will produce the same shrinkage 
as a greater degree, provided the clay is exposed to the former 
for a longer portion of time. The instrument has been, conse- 
quently, long since totally laid aside. 

Some of the most valued among the precious stones, such as 
rubies, sapphires, emeralds, jaspers, and others, are composed 
of either alumina or silica, or of the two earths in combination, 
together with different small portions of lime, or oxide of iron, 
or magnesia, &c. The different kinds of clay are most abun- 
dantly spread over the globe, forming in many situations entire 
mountains, in other places existing in vast beds, and elsewhere 
lying among other mineral substances disposed in strata. It 
has been generally held that clay results from the slow decom- 
position of silicious and aluminous rocks, which being acted o» 
by water filtrating through them, their constituent parts have, 
in the course of ages, been separated ; the lighter and finer por- 
tions remaining united at the top, while the grosser but less 
tenacious parts have been resolved into sandy deposits. 

Silica, or pure flint, which forms the second material in the 
composition of pottery, has been considered as a primitive earth. 
It is of very common occurrence in most parts of the world, in 



36 PORCELAIN MANUFACTURE. CHAP. II. 

primitive mountains. It is frequently found in great abundance 
embedded in chalk. In Scotland and Ireland it occurs in second- 
ary limestone. Flint abounds in alluvial districts in the form 
of gravel : an inexhaustible supply of excellent quality might 
be collected on some parts of the sea-coast of England, and 
particularly at and near Brighton, where there is enough of 
this material, known under the name of shingle, to serve the 
whole manufacturing wants of England for ages to come, while 
its removal would be attended with advantage to the place 
whence it should be taken. Flint is silica in a state nearly ap- 
proaching to purity, its constituents being 

Silica 98. 

Lime 0.50 

Alumina .... 0.25 

Oxide of iron . 0.25 

Loss ...... 1. 



100. 



It is usually gray, with occasional striped delineations occur- 
ring in its substance. It it obtained generally in rolled pieces, 
but often occurs in irregular shapes. It has internally a glim- 
mering lustre ; its fracture is conchoidal, and its fragments are 
sharp-edged. It is translucent. When two pieces are rubbed 
together in the dark, they emit a phosphorescent light, and 
give off a peculiar smell. We are unable to dissolve silex in 
water. This process is, however, constantly performed by na- 
ture. The investigations of Klaproth enabled him to detect 
25 grains of silex in 1000 ounces of the principal mineral 
spring at Carlsbad, in Bohemia ; and the celebrated boiling 
fountain at Rykum, in Iceland, deposits so considerable a quan- 
tity of silicious earth, that a solid cup has been formed around 
it, rising to a considerable height. This solution of silica is 
probably owing, in both these cases, to the solvent power of soda ; 
which is also present in the water. The water from the spring 
at Rykum used formerly to be projected into the air to the per- 
pendicular height of 60 or 70 feet ; but the overthrow of a 
mass of rock having since partially covered its orifice, the 
stream spouts out laterally to a distance of 50 or 60 feet. The 
heat of the liquid, after it has reached the surface, is sufficient 
to raise the thermometer to the boiling point of water ; and 
there is little doubt that the fluid must have parted with some 
portion of its heat on emerging into the atmosphere. The ca- 
pability of water, in its dense or liquid state, to assume, under 
these circumstances, a higher degree of heat than that at which 
it boils under ordinary atmospheric pressure, may be partly at- 



CHAP. II. KINDS OF CLAY USED IN POTTERIES. 37 

tributable to the depth from which it is brought, influenced by 
the same law that occasions fluids to boil at lower temperatures 
on the tops of high mountains. Silica is also found existing in 
solution in the Bath waters. 

The best flints are of a dark gray color, approaching to black, 
and having a considerable degree of transparency. Those 
which exhibit brown or yellow spots on their interior surfaces 
should be rejected, on account of the ferruginous particles 
which they contain, and which would occasion blemishes in the 
ware. Those larger masses of flint are always most preferred 
by the potter, which, being dark and clear within, are covered 
with a white crust externally. The rolled pieces which are 
taken from chalk pits are mostly of this description. 

De Saussure asserts that pure silex may be fused at a heat 
equal to 4043 degrees of Wedgwood's pyrometer ; a degree so 
far beyond any that has yet been observed, that one is at a loss 
to know upon what data the assertion is founded. 

The clay principally used in the potteries of Staffordshire is 
brought to them from Dorsetshire and Devonshire. These 
earths are both of excellent working quality, and, being free 
from any impregnation of iron, are valuable for the great white- 
ness which they exhibit when burnt. The Dorsetshire clay is 
brought from the Isle of Purbeck. It is of two kinds, distinguish- 
ed as brown clay and blue. clay: that from Devonshire comes 
from the southern part of the county, and is also of two distinct 
qualities, which are known as black clay and cracking clay. 
The clay from Dorsetshire is considered preferable to that from 
Devonshire for the potter's use ; so that it commands a price 
in the potteries equal to one eighth more than the latter. 

The good qualities of brown clay are, that it burns of an 
excellent white, and is not liable to crack during the process 
of burning. On the other hand, it is subject to the considera- 
ble imperfection of crazing, — an evil which induces some man- 
ufacturers to discard it altogether from their works. Crazing 
is a technical phrase, used to denote the cracking of the glaze, 
which is believed to arise from the imperfect manner in which 
this is capable of uniting itself with the clay composing the 
body of the vessel. This defect of crazing is not, however, al- 
ways referable to the cause here assigned, but may be owing 
equally to the faulty nature of the glaze, which may not be ca- 
pable of perfect fusion in the heat of the kiln ; or it may result 
from the error of the workmen in withdrawing the wares from 
the kiln at too early a period, and before they are properly 
cooled ; the glaze, which is in fact glass, requiring great care- 
fulness in this respect for its proper annealing, and being, with- 

D .' 



38 PORCELAIN MANUFACTURE. CHAP. II. 

out it, very liable to crack with every material variation of 
temperature to which it may be suddenly exposed. 

Blue clay combines the greatest number of good qualities, 
and is the most generally esteemed, of all the four descriptions 
here mentioned. It burns exceedingly white, forms a very solid 
quality of ware, and is capable of being advantageously com- 
bined with a greater quantity of silicious earth, or flint, than 
any of the other kinds ; a quality which is desirable, because 
the greater the proportion of silica that is used, the whiter will 
prove the ware : the limit to the use of flint being the inability 
of the clay to bear it in combination beyond a certain propor- 
tion without cracking. Both these descriptions of clay are 
much used as ingredients in the manufacture of porcelain. 

Black clay owes its distinctive color to the quantity of coaly 
or bituminous matter which it holds in combination, but which 
is entirely consumed and dissipated when the clay is submitted 
to the heat of the oven, leaving the articles of which it is com- 
posed of a very good white ; and which is, indeed, found to be 
the more perfect in proportion as the clay has originally been 
blacker. Cracking clay has acquired its name from an evil 
property of occasioning the ware to crack while undergoing 
the first application of fire. To compensate in some degree for 
this evil, the goods in which it is employed prove of an ex- 
treme whiteness. Much judgment and experience must be 
brought to the employment of this clay, that its tendency to 
cracking may be as much as possible corrected by a propor- 
tionate admixture. If clay of any description were dried with- 
out the addition of any other body, after being made sufficiently 
plastic to be modelled on the potter's wheel, it must inevitably 
crack, as the evaporation of its water will occasion it to shrink 
in the proportion of one part, in twelve during the drying. 

Another description of clay, much prized for the manufacture 
of finer kinds of earthenware and porcelain, was found in Corn- 
wall by Mr. Cookworthy, as already mentioned, and is com- 
monly denominated China clay. This is very white and unc- 
tuous to the touch, and is obviously formed by the gradual dis- 
integration of the felspar of granite. There are found in Corn- 
wall large mountains of this mineral, some of which are thus 
partially decomposed ; this China clay proves, on examination, 
to be identical with the kao-lin of the Chinese. It was found 
by Mr. Gerhard in the course of some experiments upon granite 
(which is a compound of quartz, felspar, and mica,) that the 
felspar was melted into a transparent glass, that the mica was 
found lying under it in the form of a black slag, while the 
quartz remained unaltered. 

The China clay of Cornwall is prepared by the clay mer- 



CHAP. II. KIXDS OF CLAY USED IN POTTERIES. 39 

chants on the spot where it is found. The stone is broken up 
into pieces of a small size, and then cast into a running stream : 
there the light argillaceous parts are washed off and held sus- 
pended in the water, while the more ponderous mica and quartz 
remain at the bottom of the stream. At the end of the rivulet 
the water is stopped by a dam, and the pure clay gradually sub- 
sides. When this deposit is completed, the clear water is drawn 
off, and the solid matter dug out in square blocks, which are 
placed on shelves, and exposed to a continued current of air 
until sufficiently dry to be packed in casks for shipment. This 
clay, which is then in the state- of a fine powder, is very 
smooth, and of an extreme whiteness. Mr. Wedgwood found 
by analysis that it contains sixty parts of alumina and twenty 
parts of silica. The manufacturers are required to pay a much 
higher price for this than for any other of our native earths, 
but for some finer purposes it is altogether indispensable. 

A portion of undecomposed Cornish felspar is often added to 
the clay, on account of its fusibility and tenaciousness, by which 
it binds, as it were, the whole ingredients more closely together. 
The fusible quality of felspar is owing to the presence of about 
an eighth part of potass. If this alkaline substance be sepa- 
rated by decomposition, as is the case with the China clay above 
described, the fusibility no longer exists, and the body remains 
unaltered in the greatest heat of a porcelain furnace. The use 
of this material has of late been very much increased in our 
porcelain works. It is a curious and very useful fact, that al- 
though neither clay, flint, nor lime can be separately melted, 
yet when mixed together in due proportions, the mass is fused 
without difficulty, the one mineral acting as a flux to the other. 

Steatite, or soapstone, has of late years been very much em- 
ployed in the composition of porcelain. When present, in even 
a small proportion, it limits the contraction of the ware in the 
furnace. Steatite is a sub-species of mica, which is found 
abundantly in Cornwall, and is met with also in the island of 
Anglesea. The mineral which forms the porcelain earth of 
Baudissero, was long considered to be a superior kind of clay, 
until it was discovered by M. Geobert that it contains not a par- 
ticle of alumina in its composition. This chemist, on endeavor- 
ing to convert the substance into alum, found, to his great sur- 
prise, that he obtained only crystals of sulphate of magnesia 
(Epsom salts). Proceeding thence to analyze it carefully, he 
ascertained its composition to be, magnesia 68, carbonic acid 
12, silica 15*6, sulphate of lime 1*6, water 2*8. The soapstone 
of Cornwall differs from this substance, yielding on analysis, 
magnesia 44, silica 44, alumina 2, iron 7*3, magnesia 1*5, 
chrome 1*2. It also contains traces of lime and muriatic acid. 



40 PORCELAIN MANUFACTURE. CHAP. II. 

In a published letter addressed by M. Proust to M. Vauque- 
lin from Madrid, mention is made of a beautiful kind of porce- 
lain produced in that city, and which is described to be of a 
texture even harder than the porcelain of France. Instead of 
employing the kao-lin, the body of the ware is made with spu- 
ma maris, a species of pot-stone found in the neighborhood of 
Madrid, and the glaze is composed of felspar brought from Gal- 
licia. The pot-stone when taken from the quarry is sufficiently 
soft to admit of its being cut with a knife like soap. Besides 
magnesia, silex, and some particles of argil and lime, it con- 
tains a portion of potass, the presence of which, in the com- 
petent opinion of M. Proust, contributes not a little to the su- 
perior quality of the manufacture. 



CHAP. III. 



ON THE PREPARATION OF MATERIALS. 

Dilution of Clay. — Chemical Examination of Water necessary. — Rain Wa- 
ter.— Carefulness of German Manufacturers. — Blunging.— Machinery.— 
Preparing Flints. — Burning. — Breaking. — Grinding. — Dry Grinding. — 
Brindley's Improved Mill— Chert. — Care required in selecting Grinding 
Stones.— Dilution of Flint-Powder. — Proper Consistence of Dilution.— Ad- 
mixture in due Proportions. — Affinity of Alumina for Silica. — Slip, — 
Slip-Kiln. — Method of evaporating superfluous Moisture. — Working the 
Paste. — Time necessary for tempering it. — Proportions wherein Clay and 
Flint are united. — Difficulty of ascertaining this. — Slapping. — French 
Manufacturers. — Proportions of Ingredients used by them. — Kao-Lin. — 
Flint. — Gypsum. — Broken Porcelain. — Calcined Bones.— Tender Porcelain. 
— Its Composition. — Porcelain Earth used in Berlin. — French Potters buy 
their Materials ready mixed.— Advances on this Plan.— Ineligible in Eng- 
land. 

In preparing the clay, the first operation of the pottery is 
that of mixing it with water to the consistence of cream. It 
is well known, that water collected from springs, and from 
many streams, contains various foreign matters, some of which 
would be injurious to the composition of porcelain. It is there- 
fore necessary to examine chemically the properties of water 
before it is employed for this purpose, in order to make choice 
of that which is purest ; and to correct, by some of the well- 
known means, any bad qualities that may be present. The 
French manufacturers are accustomed to employ only rain 
water, whose near approach to purity fits it for the object. In 
Germany, still more precise in his operations, the manufacturer 
prepares his materials only twice in the year, at the vernal and 
autumnal eqmnoxes ; persuading himself that at these seasons 
there is some peculiarity in the rain which better qualifies it for 



CHAP. III. PREPARATION OF MATERIALS. 41 

the purpose of his manufacture. Although the grounds for this 
nicety are not apparent, it would savor of presumption to at- 
tribute the practice entirely to prejudice. The observations of 
men practically engaged in manual or chemical operations have 
frequently led to improvements in processes, long before the 
reasons whereon these should have been founded have been re- 
vealed by scientific researches. 

The mixing of the clay, which is called blunging, is effected 
in a trough five feet long, three feet wide, and two and a half 
feet deep. In order fully to break down the clay, and incor- 
porate it with the water, a long wooden instrument, formed 
with a blade at one end and a cross handle at the other, is 
moved violently about hi the trough in all directions, so that 
this becomes an operation of great labor. In large establish- 
ments, where machinery is adopted for the abridgement of la- 
bor, the blunging is thus effected : — The clay is thrown into a 
cast iron cylinder, four feet deep, and twenty inches in diam- 
eter. Through the centre of this cylinder runs an upright 
shaft, furnished with knives placed as radii at right angles to 
the shaft, but so arranged upon it that their flat sides are in 
the plane of a spiral thread, so that by the revolutions of the 
shaft, the knives perform the double office of cutting what- 
ever stands in their way, and of forcing downwards the con- 
tents of the cylinder in the manner of a screw. Another set 
of knives is inserted in the interior surface of the cylinder, 
and these extend to the shaft in the centre, parallel to, and 
corresponding with, the revolving knives : thus the two sets, 
the one active and the other passive, have the effect of shears 
in cutting the clay into small pieces ; while this, in its reduced 
state, is at the same time forced through an aperture at the 
bottom of the cylinder, and transferred to a vat for the purpose 
of being mixed with water ; a process which this previous di- 
viding of the clay is found materially to facilitate. 

The vat where this mixture is performed is likewise of a 
cylindric form, its diameter being equal to four times its depth. 
In the centre of this vat, also, a perpendicular shaft is inserted, 
furnished with cross arms or radii, one below the other. These 
cross arms are connected by upright staves, giving the appear- 
ance of two opposite gates hung upon the central shaft. These 
revolve within the cylinder ; and as they are partially immersed 
in the pulp, the constant agitation mixes all the finer particles 
of clay with the water, while stony particles of greater magni- 
tude fall to and remain at the bottom. The pulp, now mixed to 
the consistence of cream, is passed off from the vat through a 
series of sieves of increasing degrees of fineness, which are 
worked to and fro by machinery ; thus a separation is effected 

D2 



42 PORCELAIN MANUFACTURE. CHAP. Ill, 

between the grosser parts and that portion which is fitted to 
enter into the composition of the ware. 

The next process is that of preparing the flints. These are 
first burnt in a kiln constructed for the purpose, and which 
very much resembles an ordinary lime-kiln, being of a conical 
shape, and about nine feet deep. While the flints are yet red- 
hot, they are removed , from the kiln, and in that state are 
thrown into cold water ; by means of which their attraction of 
aggregation is lessened, so as to facilitate greatly the subse- 
quent operation of grinding : they are next broken, either by 
manual labor, or by machinery. In the latter case they are 
placed upon a strong iron grating, and there struck by ham- 
mers, until sufficiently reduced in size to fall through the gra- 
ting to a receiver, whence they are conveyed to the flint mill. 

In order to expedite the process, and at the same time to 
grind the flints finer, a quantity of water is thrown with them 
into the mill. Another good attending the presence of water 
in this grinding operation, is the preservation of the health of 
the workmen. Before the adoption of this method, the atmo- 
sphere of the room became charged with the finer particles of 
flint, which, adhering to the lungs, frequently occasioned dis- 
tressing and sometimes fatal diseases to the workmen. This 
great improvement was effected by the illustrious Brindley, 
who likewise invented the mill now used in the process. This 
is a large circular vat, about thirty inches deep, having a cen- 
tral step fixed in the bottom to carry the axis of a vertical 
shaft. The moving power is applied to this shaft by a crown 
co.g wheel placed on the top. At the lower part of the shaft, 
and at right angles to it, are fixed four arms, upon which the 
grinding stones are fixed ; large blocks of stone of the same 
kind being likewise placed in the vat. These stones are a very 
hard silicious mineral, called chert, which is found in abun- 
dance in the neighborhood of Bakewell, in Derbyshire. The 
broken flints being then introduced and completely covered 
with water, the axis is made to revolve with great velocity, 
when the calcined flints are speedily reduced to an impalpable 
powder. 

The nature of the grinding stones used in these flint mills is 
of considerable importance ; for should they contain any calca- 
reous carbonate, they will be abraded ; some part of their sub- 
stance will mix with the flint, and consequently with the body 
of the wares, and thus occasion very serious injury to the man- 
ufacturer. Some years ago, a very heavy loss was sustained by 
some potters, who had purchased flints ground in a mill the 
stones of which contained carbonate of lime. 

When the flints are thus sufficiently ground, the semi-fluid 



CHAP. III. PREPARATION OP MATERIALS. 43 

is transferred to another vat, also constructed with an upright 
shaft furnished with arms or vanes for the purpose of agitation ; 
and a considerable quantity of water being added, the moving 
power is applied, and the whole violently agitated. The pro- 
cess occasions the grosser and weightier particles to take their 
place at the bottom, while the finer portion remains in suspen- 
sion above ; and in this state is passed for subsidence to a reser- 
voir, whence in due time the supernatant water is drawn off 
through apertures provided for the purpose. 

The dilution of clay is held to be of the* proper consistence 
for mixing, when a quantity that will fill a pint measure 
weighs twenty-four ' ounces ; and that of the flints is equally 
considered suitable for use, when the same bulk is brought to 
weigh thirty-two ounces. It is by their specific gravities, that 
is, by the comparative densities of these dilutions, as indicated 
by weighing an equal bulk of each, that the manufacturer is 
enabled to ascertain the real proportions of the materials, and 
to combine them in the degrees which his experience leads him 
to employ for the composition of various kinds of pottery ; and 
too much*nicety can hardly be given to this important part of 
his labors. 

The dilutions of clay and flint being brought together in 
suitable proportions, and intimately united by agitation, the 
mixture is passed, while in a state of semi-fluidity, through dif- 
ferent sieves, in order to separate any remaining impurities, to- 
gether with such portions as have not been sufficiently ground. 
By these means the mass presents the utmost uniformity and 
smoothness throughout. The affinity which alumina has for 
silica, under all circumstances, is so great, that they will unite 
even in the humid way, forming a kind of mortar ; and when 
this becomes hardened by time, it is thereafter incapable of de- 
composition by the action of the atmosphere. 

This fluid mixture of clay and flint is called slip, and, after 
passing through the sieves, is pumped to the slip kiln. This is 
a kind of trough formed of fire-bricks ; its size varies according 
to the extent of the manufactory, being of the length of forty 
to sixty feet, from four to six feet wide, and about twelve to 
eighteen inches deep. Flues from fire-places pass under the 
whole extent of the troughs, in which the fluid is made to boil, 
and the process of evaporation is slowly conducted, so as to 
produce an uniform consistency throughout the mass. This 
evaporation must be very carefully attended, and the mass fre- 
quently stirred and turned over, otherwise, from the imperfect 
manner in which it conducts heat, the portion in contact with 
the bricks would become improperly hardened, while the re- 
mainder would continue fluid ; in addition to which, flint being 



44 PORCELAIN MANUFACTURE. CHAP. Ill* 

specifically heavier than clay, the former would in the first part 
of the process, and while the slip is yet fluid, have a natural 
tendency to subside to the bottom, and thus render the com- 
position of the mass unequal. 

The evaporation is never carried beyond a certain point in 
the kiln ; for should the mass become too dry, it would be im- 
possible to knead it properly, or to mould it on the wheel into 
any of the forms which it is desired to create. The place 
where this evaporation is performed is called the slip-house. 

When the clay or paste is remqved from the slip-kiln it con- 
tains a great number of air-bubbles, and must be well incorpo- 
rated together or tempered by working ■ or beating it with 
wooden mallets. It is next cut with a kind of spade into small 
pieces, which are thrown upon the mass with all the strength 
of the workmen, and these operations are persisted in until it 
is supposed that their further continuance would not bring the 
whole to a more complete state of consistence. 

The mixture, when brought to this state, should be suffered 
to remain in a mass for a considerable time before it is used ; 
the material by this course becomes much more intimately 
united than can ever be effected by mechanical means. It is 
to be feared that, although the English potters are fully aware 
of this fact, they yet fail to adopt so eligible a practice, which, 
as it calls for the employment of greater space, time, and capi- 
tal, is neglected for other advantages, which, if not so great in 
an extended point of view, are certainly more immediate. 

It is not possible to state the precise proportions wherein the 
clay and flint are brought together in our English potteries. 
Each manufacturer has in this respect his own practice, which, 
esteeming it as the best, he endeavors to keep profoundly se- 
cret ; and, besides, the proportions necessarily vary With the 
quality and properties which it is desired to give to the manu- 
facture. Vauquelin informs us that silex forms at least two 
thirds of all kinds of pottery ; alumine from one fifth to one 
third; lime from 1 -500th to l-2000th part; and iron from the 
smallest conceivable quantity up to twelve and sometimes even 
fifteen per cent. The presence of the two latter bodies is ac- 
cidental, arising from the natural composition of the materials, 
and in particular the oxide of iron, when present in any sen- 
sible degree, renders the clay unfit for all purposes, except that 
of forming the common red ware. 

Parkes, whose practical essay on the making of earthenware 
and porcelain is founded on his own personal observations, 
made during a residence of some years' continuance at the seat 
of manufacture, is yet so little able to be precise upon the sub- 



CHAP. III. PREPARATION OF MATERIALS. 45 

ject of proportions, that he tells us flint forms a fourth, a fifth, 
or a sixth part by weight of the prepared paste. 

Some portion of the china-clay of Cornwall enters into the 
composition of every better kind of earthenware, except only 
the cream-colored sort. This ingredient is sometimes added to 
the mass, and blunged with it, and at other times is blunged 
separately and mixed in the required proportion with the slip. 

The clay or paste, when taken for use, undergoes the pro- 
cess of slapping. This labor is assigned to "a man of con- 
siderable strength, who proceeds by placing a lump weighing 
from fifty to sixty pounds upon a convenient slab or bench. 
The mass is then cut through with a thin brass wire, one end 
of which is held in either hand, while the part between is 
forced through the clay, which separates as easily as if it were 
cut with a knife ; then taking up with both hands the piece 
thus separated, and exerting his utmost strength, he hurls it on 
the rest of the mass ; and this operation is repeated until the 
whole lump exhibits a perfectly smooth and close appearance 
wherever it is cut. So complete is the incorporation of the 
whole mass by this means, that if, at the commencement of the 
process, two pieces of clay of different colors are taken, the 
lump, at its completion, will be of one uniform hue, intermedi- 
ate to the two original colors. This laborious operation is one 
of the very first necessity, in order completely to expel every 
air-bubble, however minute, remaining in the clay, and which 
could not be so thoroughly driven out by its previous beating in 
the larger mass when taken from the slip-kiln. If the air 
were not thus thoroughly expelled, it would become so much 
rarified and expanded in the oven, that it would force out a 
passage for itself, and by blistering, spoil or much injure the 
goods. 

Some of the more considerable among the potters, who em- 
ploy steam power for blunging the clay and grinding the flints, 
perform this operation of slapping by the same agency, saving 
thereby both time and labor. In this case the expulsion of the 
air is effected by mechanical pressure, and the office is per- 
formed with perhaps as much efficiency as by hand. 

Having undergone all these preparations, the clay is now fit 
for being shaped upon the wheel or fashioned by the aid of 
moulds into all the diversified forms which fancy may desire. 
This branch of the art is divided into three different depart- 
ments — throwing, pressing, and casting — either of which is 
used according to the form of the article manufactured. 

The manufacturers of porcelain in France do not use so 
much secrecy as is preserved in our own potteries, with re- 
spect either to the materials whereof their ware is compound- 



46 PORCELAIN MANUFACTURE. CHAP. HI. 

ed, or to the proportions wherein these are employed. The 
clay which forms five parts in six of the whole mass, is the 
porcelain earth already mentioned as being identical with the 
kao-lin of China ; to this are added in certain proportions flint 
and gypsum (plaster of Paris), both calcined and ground ; and 
fragments of broken porcelain, which must be white, also 
ground to a fine powder. One rule for forming this composi- 
tion assigns nine parts each of flint and broken porcelain, and 
four parts of calcined gypsum, to each one hundred parts of 
porcelain clay. Another authority recommends five parts of 
gypsum and only eight parts of ground porcelain ; while the 
flint and clay are used in the same proportions as in the first 
rule. If at any time the manufactory should not afford broken 
porcelain for the purpose, it is recommended that pieces be 
compounded, about a quarter of an inch thick, of the other 
three ingredients, wherein the proportions of gypsum and flint 
are augmented ; and these pieces, having been previously con- 
verted into porcelain by baking, are to be ground and mixed in 
the above-mentioned proportions with the other ingredients. 

It has of late years been the practice of some English manu- 
facturers to use a considerable proportion of calcined bones, to- 
gether with a small quantity of gypsum, in combination with 
china-clay, flint, Cornish stone and enamel. By this means 
porcelain of a brilliant and very transparent white is produced, 
which, however, is deficient in density, and very liable to- crack 
on the application of hot liquids. 

Several among the chemists and scientific manufacturers of 
porcelain in France have given recipes for the composition of 
tender porcelain, although this description of ware is no longer 
made in that country. 

This kind of porcelain will support, without softening, a 
greater degree of heat than suffices to melt glass. It is semi- 
transparent, has a vitreous fracture, and returns a clear sound 
when struck by a hard body. It is harder but not so brittle as 
glass, and bears, without injury, sudden and very considerable 
alterations of temperature. 

M. Brongniart recommends a mixture of one part of pure 
white clay, with three parts of a frit compounded of nitre, 
soda, alum and selenite (sparry gypsum), together with a large 
proportion of ferruginous sand and a little common salt. The 
ingredients of this frit are to be calcined together, and the 
whole intimately kneaded ; when cold, the compound is to be 
reduced to powder, and in that state mixed with the clay. 

This paste is not so cohesive or viscous as that which forms 
hard porcelain, and greater carefulness is, therefore, called for 
in fashioning vessels with it. Lime and selenite, or any similar 



CHAP. III. PREPARATION OF MATERIALS. 47 

earths which, if fused by themselves, produce a transparent 
and colorless glass, may answer the same purpose as the frit 
just mentioned. In making choice, however, of the compound 
to be thus used, it must be borne in mind, that the paste must 
not be more stubborn in resisting fire than the seggars, or 
vessels wherein it is inclosed during the baking, and no greater 
proportion of any substance that promotes fusion must he used 
than can be supported by the clay without having its cohesive- 
ness greatly diminished. 

The porcelain earth used in Berlin is compounded with sili- 
cious sand and sulphate of lime in crystals. The constituents 
of their flux are varied in the proportions according to the 
quality of the ware it is intended to produce. In the greater 
part of the German manufactories felspar is used, and some 
employ a calcareous sand. 

When tender porcelain was made in the works at Sevres, a 
small portion of arsenic entered into its composition. This was 
found very hurtful to the workmen. Few of the turners or 
moulders, after following their employment for some years, es- 
caped severe pulmonary complaints ; and to this disadvantage is 
ascribed the order of the French government under which this 
branch of the manufacture has been discontinued in that estab- 
lishment. 

Individual manufacturers of porcelain in France avoid all the 
labor of preparing their materials, and purchase these in a 
state of readiness from establishments at Limoges where the 
best porcelain earth is found. The price of the compound, 
when delivered in Paris, or at an equal distance from the place 
of preparation, does not exceed three sous — about one penny 
halfpenny of our money — per pound. 

This arrangement must considerably simplify the operations 
of the manufacturers, and lessens the amount of capital which 
they must employ in the establishment of their works ; but it 
is doubtful whether the accompanying disadvantages are not 
fully equivalent to these benefits. There are many reasons to 
render such a plan ineligible in this country. 



48 



PORCELAIN MANUFACTURE. 



CHAP. IV. 



CHAP. IV. 



ON THE FORMATION OF UTENSILS. 

Throwing.— Potter's Lathe.— Thrower.— Mode of Proceeding.— Profiles.— 
Slurry.— Gauges.— Turning Lathe.— Turning and Smoothing.— Moulding 
Dishes, &c— Tools.— Steam Machinery.— Engine-Lathe.— Milled Edges.— 
Handler.— Formation of Handles, Spouts, &c— Pressing.— Small Orna- 
mental Figures.— Mode of affixing them.— Method of making Moulds.— 
Boiled Plaster.— Great use of Gypsum in making Moulds.— Stoves.— Mod- 
elling. — Qualifications requisite for a Modeller. — Increasing Skill of Art- 
ists.— Fostered by Mr. Wedgwood.— Mould-Maker.— Method of his Work- 
ing. — Casting.— Carefulness required in Drying. 

The operation of throwing consists in shaping such vessels 
as have a circular form, and is performed upon a machine call- 
ed a potter's lathe. 

This consists of an upright shaft, about the height of a com- 
mon table, on the top of which is fixed a circular piece of wood, 
whose breadth is sufficient to support the widest vessel that is 
to be made. The bottom of the shaft runs in a step, and the 
upper part in a socket a little below the circular board, so that 

Fig. 1. 




the shaft and board turn together. The shaft has a pulley fixed 
upon it by means of which it is turned, an endless band passing 
round the pulley from a wheel placed at a short distance, and 
which is ten times the diameter of the pulley ; this wheel when 
turned by a handle sets the lathe in motion. 

The clay to be thrown is first cut and weighed and formed 
into a ball. It is then placed on the face of the circular board, 
which being put in motion, the thrower, dipping his hands from 
time to time into water, or slip, that the clay may not adhere to 
them, fashions it first into a long thin column, which he forces 
again down into a lump, and continues these operations until as- 
sured that no air-bubbles can possibly remain in the body of the 
clay. He then directs that the speed of the wheel shall be mode- 



CHAP. IV. FORMATION OF UTENSILS. 49 

rated, and proceeds to give the first form to the vessel. This 
is done either by his fingers alone, or with the aid of an instru- 
ment shaped according to the desired form. The instruments 
employed for this purpose are called profiles or ribs. By the 
assistance of one of these, the inside is smoothed and made to 
assume the requisite shape, and any inequalities, technically 
called slurry, are removed. When it is wished to make any 
number of vessels exactly similar to each other in shape and 
dimensions, certain pegs are fixed as a gauge without the cir- 
cumference of the revolving board, but placed in such a man- 
ner, that whenever the plastic clay is brought to coincide at 
the requisite points with the gauge, the thrower knows that 
the article has attained the proper dimensions. 

In this manner most circular-shaped vessels are formed. 
When finished to the artist's satisfaction, he proceeds to re- 
move his work, cutting it from the lathe by passing a thin brass 
wire through the lowest part of the clay. The vessel is then 
lifted off and placed on a board or shel£ where it is left to dry 
partially before it is farther smoothed and shaped in the turn- 
ing-lathe. 

When the vessel is so far dried as to be in that particular 
state of hardness well known to the workmen, and which is 
called the green state, it is in the most favorable circumstances 
for the performance of the remaining operations of turning and 
smoothing, for being furnished with handles, spouts, and such 
appendages as cannot be affixed in its first formation. 

For making circular dishes, plates, saucers, or shallow bowls, 
and other vessels of that class, a plaster mould is used. This 
is slightly sprinkled with powdered porcelain, sifted through a 
fine cloth, and placed on the block which surmounts the upright 
spindle of the lathe. The block being then set in motion, the 
clay is fashioned in the first place by the hand of the workman, 
which presses it against the mould, and afterwards with a pro- 
file to give the requisite internal form. If any ledge or foot is 
required, it is affixed afterwards with slip, in the manner here- 
after described as employed for joining handles and spouts. All 
superfluous parts are cut away, and the whole is finished by 
means of a horn tool and a damp sponge. When sufficiently 
dry to be taken from the moulds, the edges are pared with a 
sharp knife, and the pieces are slightly polished by the hand. 
After this, they are placed in piles of four, six, ten, or more, ac- 
cording to their weight and solidity, and are left to harden, 
preparatory to their being put in the oven. 

The turning-lathe of the potter is similar to that used by the 
turner in wood. The end of the spindle has a screw thread, 
upon which are screwed chucks of wood, tapered in their form, 

E 



50 PORCELAIN MANUFACTURE. CHAP. IV. 

and differing in their diameters according to the size of the ar- 
ticle to be turned. The tools employed are of different sizes, 
from a quarter of an inch to two inches broad, and six inches 
long : they are made of iron, the cutting end being turned up 
about a quarter of an inch, and ground to a good edge. 

The vessel to be turned being fixed upon the chuck, and mo- 
tion communicated to the lathe, the turner proceeds to reduce 
the substance of the clay in such parts as are required, to form 
rings and rims upon the vessel, and generally to attend to those 
little niceties of shape which are not easily attainable on the 
throwing-lathe. When this is completed, a contrary motion is 
given to the spindle, the turner applies the flat part of his tool 
to the vessel, and using a gentle pressure, produces the requi- 
site smoothness of surface and solidity of texture. 

In those considerable establishments which are furnished 
with a steam-engine, the throwing and turning lathes are both 
actuated by it. To the first of these machines motion is then 
given by means of two upright cones, placed opposite to each 
other ; the apex of the one answering to the base of the other. 
One of these cones receives motion directly from the engine, 
and communicates it by means of a leather strap to the other. 
By this arrangement the horizontal strap has always an equal 
tension to whichever parts of the cones it is applied, the en- 
largement of the one answering to the diminishing diameter of 
the other ; but the speed given to the lathe will depend upon 
the position on the driving cone which the strap occupies : if 
this is at the small part, the driven cone, and consequently the 
revolving-board of the lathe, will travel more slowly, and its 
revolutions will, on the other hand, be accelerated in proportion 
as the strap is made to occupy the larger part of the driving 
cone. When the strap takes its position on the largest part of 
this, it will apply to the smallest part of the driven cone, and 
the speed of the lathe will be at its maximum. The position of 
the strap upon the cone is regulated at pleasure by a winch, a 
boy in attendance upon which follows the directions of the 
thrower. When the article is finished, the strap is thrown off 
the driving cone, and the motion of the lathe of course ceases. 

The turning lathes, when actuated by the steam-engine, are 
arranged in a row, the whole length of the room, through 
which runs a horizontal shaft, and this has fixed upon it, oppo- 
site to each lathe, a drum, straps on which connect the shaft 
with the lathes. The speed of the lathes is regulated by pro- 
viding pulleys of different sizes, upon any one of which the 
strap may be guided by the turner during the revolutions of the 
spindle. When the turning of the vessel is finished, the strap 
is transferred to another pulley connected by a crossed strap 



CHAP. IV. FORMATION OF UTENSILS. 51 

with the spindle, which by that means has a reversed motion 
communicated to it, and the article under operation is smooth- 
ed and polished in the manner already described. 

A milled edge is given to earthenware in what is called an 
engine lathe, where, in addition to the rotary motion communi- 
cated to the article, it has likewise a horizontal movement to 
and fro, enabling the workman to make the requisite incisions 
at proper and definite intervals. 

When the vessels are taken from the turning-lathe, they are 
delivered to the handler, who fixes upon them handles, spouts, 
and other appendages of that nature. These are affixed to the 
vessels by means of slip, with which the parts brought into con- 
tact are moistened. Being then left for a short time to dry, the 
junction is found to be perfect ; and with a knife the superflu- 
ous clay is removed from about it : the whole vessel is next 
cleaned with a damp sponge, which moistens the whole equally, 
and gives uniformity to its appearance. 

Handles, spouts, and objects of that nature are made with, the 
aid of a press, consisting of a small metallic cylinder, which has 
an aperture in the centre of its bottom, to which plugs with dif- 
ferently shaped orifices are fitted. It has also a piston, actuated 
by a screw, which works through an iron bow attached to oppo- 
site sides of the cylinder. The aperture in the bottom being 
furnished with a plug of the desired form, and the cylinder 
charged with clay, the piston is inserted, and by the turning of 
the screw is forced down upon the clay, causing it to protrude 
through the aperture in the proper shape. This being cut into 
lengths, and bent into the required form, is, when sufficiently 
dry, affixed to the vessel as already mentioned. If the clay is 
required to take a hollow cylindrical form, as it must for spouts, 
a pin of the same diameter as it is wished to give the tube is 
fixed above the centre of the plug. It is obvious that some or- 
namented spouts cannot be made by this means. For forming 
such, two moulds of plaster must be prepared in the manner 
hereafter described, one half of the figure being impressed in 
each of the moulds, which must fit together accurately. Clay 
is then forced into each mould, and the superfluous quantity 
being cut away, leaving still a small portion above the level of 
the moulds, the two are brought firmly together to unite the 
two halves of the article. The mould is then divided, the clay 
is removed, and finished as to its form with suitable tools by the 
workman. This is the operation known under the name of 
pressing. The moulds for the purpose are made with plaster 
of Paris, (gypsum, or the native sulphate of lime,) the peculiar 
fitness of which material for the purposes, arises from its prop- 
erty of absorbing water with very great rapidity, so that the 



52 PORCELAIN MANUFACTURE. CHAP. IV. 

ware inclosed within it speedily dries in a sufficient degree to 
deliver itself (according to the workman's phrase) easily from 
the mould. 

Small ornaments, such as figures, animals, foliage, and the 
like, are more conveniently made by pressing the clay in plas- 
ter moulds, or otherwise these are made of copper, which must 
previously be slightly smeared with oil, in order to insure the 
easy delivery of the ornaments. These are then affixed to the 
vessel by means of slip, according to the method already de- 
scribed. It is in this manner that drinking jugs are so com- 
monly ornamented with figures in relief. 

In order to prepare the plaster for making moulds, it is first 
ground between a pair of stones, in a mill exactly similar to that 
employed for grinding wheat ; it is next boiled in order to drive 
off the water which forms a considerable constituent part of its 
natural substance. There is an appearance of absurdity in thus 
speaking of boiling a dry earthy substance ; but the workmen 
who use the term, are not very far wrong in their expression. 
To all appearance, ebullition goes rapidly on in this operation, 
and there is a disengagement of steam as in the boiling of watery 
fluids. When this process is completed, the substance is al- 
ways called boiled plaster. The evaporation is conducted in 
long brick troughs, having a fire flue running under their en- 
tire length, in a manner similar to the slip-kiln. The man who 
superintends the process, is obliged to wear a handkerchief over 
his mouth and nostrils, to prevent the passage of any particles 
of the gypsum to his lungs, or stomach, such a circumstance 
having been found very prejudicial to health. 

The plaster when thus deprived of its water becomes a soft 
impalpable powder, but when its natural proportion of water is 
again added, so strong is its affinity for that liquid, and such its 
capacity for again combining with itself that portion of which it 
has been deprived, that it attracts and condenses the whole, and 
will immediately set into a hard and very compact mass, pecu- 
liarly suitable for the purpose here required. 

The consumption of plaster of Paris, in making moulds for 
plates and dishes is so considerable, that in the district compre- 
hending the Potteries, in Staffordshire, many tons are annually 
worn out and thrown away as useless. 

Articles placed in these moulds part with moisture so rapidly, 
that when put in a very temperate stove, they will become dry 
enough for removal in two hours, and each individual mould is 
capable of being used for forming four or five different articles 
in the course of a working day of twelve hours. The stove 
wherein these moulds, with their contents, are placed to dry, is 
a small room built with bricks, and having wooden shelves 



CHAP. IV. FORMATION OP UTENSILS. 53 

ranged round it, and over one another from the floor nearly to 
the ceiling ; it is heated by warm air conducted through it in 
an iron pipe. 

Moulds for producing simple wares, such as plates and dishes, 
and generally for such objects as are formed by pressing, are 
simple in their construction ; but others, which are used for the 
third department, that of casting, call for much more art and 
skill for their invention and execution. For these, the taste of 
the modeller is put in requisition, calling for the exertion on his 
part, of a high degree of skill and ingenuity in forming patterns, 
and adapting to them appropriate ornaments. To be a perfect 
modeller, in the higher branches of the art, a man should have 
an acquaintance with the best productions of the classic climes 
of Greece and Rome; he should be master of a competent 
knowledge of the art of design ; his fancy glowing with ori- 
ginality, tempered and guided by elegance and propriety of 
feeling, and restrained by correctness of taste and judgment. 
To a man thus gifted, the plastic and well-tempered material 
wherewith he works offers little of difficulty in the execution 
of his conceptions. 

In the most considerable works, and where the proprietors 
are ambitious of excelling, modellers are kept in constant em- 
ployment. Other manufacturers content themselves with buy- 
ing new moulds from artists who compose them on speculation, 
and who are sometimes so little scrupulous as to dispose of the 
same pattern to several different purchasers. 

For want of due encouragement, high degrees of excellence 
in this art were formerly not of frequent occurrence. Mr. 
Wedgwood, to whom the porcelain manufacture of England 
owes so many and such various benefits, proved that talent in 
this branch of art needed only for its development to be fostered 
and encouraged with liberality. This patriotic individual paid 
the sum of four hundred pounds to Mr. Webber for modelling 
the Portland or Barberini vase, although the work called for no 
original or inventive powers. Since that time, English model- 
lers have attained to such a degree of excellence, that it is said 
any good modeller, with one qualified assistant, would be able 
to achieve, in the short space of two weeks, the task which oc- 
cupied Mr. Webber for many months, and which was viewed, 
at the time, as an honorable proof of both his talent and in- 
dustry. 

The model, when moulded by the hand, must be trimmed, 
carved, touched, and retouched with suitable tools, constructed 
of metal or wood, and sometimes even of ivory, for the more 
perfect finishing of the whole composition. 

When thus completed, the model passes into the hands of the 

E2 



54 PORCELAIN MANUFACTURE. CHAP. IV. 

mould-maker, whose occupation is quite mechanical and distinct 
from that of the modeller. A strong casting of clay is first 
formed and securely fixed round the model, leaving sufficient 
space between for the substance of the mould. Proper propor- 
tions of plaster of Paris and water are then placed in a jug, and 
the mixture is briskly stirred, so that the water may thoroughly 
pervade the whole, which is then poured gently upon and 
around the model, covering it in every part to the requisite de- 
gree of thickness. Upon this some heat is sensibly given out 
by the plaster, and the whole is very shortly converted into a 
hard compact mass, easily separable from the model, and found 
to exhibit a perfect impression of its form, and the minutest 
niceties of its ornaments. The mould is, after this, placed' in a 
stove to be thoroughly dried, and is then fit for use. 

Many articles were formerly made by casting, which are 
now produced by the operation of pressing last described. 
Casting is now employed only for the formation of irregular- 
shaped vessels, where much nicety is required, and which need 
not have much strength. The casting operation is performed 
by intimately mixing the united clay and flint with very pure 
water to the consistence of cream. On pouring this dilution 
into the mould, the plaster quickly absorbs water from that por- 
tion which lies in contact with its surface, hardening it to such 
a degree, that on the central and still fluid part being poured onv 
a coating of clay will remain attached to the mould. This 
coating having been allowed further to dry during a short time, 
a second charge of diluted clay, but the consistence of which is 
much greater than the creamy fluid first used, is poured in, and 
adds to the substance of the first deposit. Having remained in 
the mould sufficiently long for this purpose, the remainder of 
the semi-fluid is poured off, and the mould, with its contents, is 
set in a stove : when sufficiently dry to allow of separation, the 
article is taken from the mould, and left until it is brought to 
the green state, when all imperfections are rectified by the 
workman, whose skill is exerted to render the vessel as smooth 
and as perfect as possible. 

It is essential to the excellence of all kinds of earthenware, 
that the means used for drying it previous, to the baking should 
produce an uniform evaporation throughout its entire substance. 
If too much heat were artificially employed, the surface might 
be hardened, while the internal part remained moist ; and this 
would be attended with disastrous consequences in the oven, 
owing to the unequal contraction that would then ensue. It is, for 
this reason, necessary to allow time for the gradual dispersion 
of moisture, which, however, may be advantageously expedited, 



CHAP. V. OP FIRING AND GLAZING. 55 

by placing the pieces upon plaster shelves, whose absorbent 
property would occasion the requisite drying in a shorter time, 
and with increased regularity and uniformity. 



CHAP. V. 

ON THE PROCESSES OF FIRING AND GIAZING. 

.Seggars. — Proper Materials for these wanting in England. — Not so in 
France. — Nungarrow Work. — Why discontinued. — Great Estimation of 
its Wares. — Cause of Superiority. — Use of Seggars. — Their Forms. — Mode 
of using them. — Sevres Manufactory. — Improved Furnace. — Its advan- 
tages. — Description. — Chinese Method of Firing. — Construction of their 
Kilns. — Care required in Baking. — Duration of Process. — Oven-Man. — 
Trial Pieces. — Annealing. — Biscuit. — Wine Coolers. — Glazing. — Compo- 
sition of Raw Glazes.— Bad effects of some of these to the Public— To the 
Workmen. — Pernicious use of Ardent Spirits. — Glazes invented by M. 
Chaptal. — By Mr. Rose. — Porcelain Glazes. — French Glazes. — Palissy. — 
His Experiments on Enamelling. — His Perseverance and Sufferings. — His 
Success, and continued Firmness under Persecution. — Inferior Glazes.— 
Low-priced Wares.— Gloss-Oven. — Regulation of Temperature.— Qualities 
that determine the Excellence of Porcelain.— Stone-Ware. — Its Compo- 
sition. — Lambeth Potteries. — Modes of Glazing. 

In the state whereto the vessels are now brought, they are 
ready to undergo the first application of fire in the oven. For 
this purpose they are placed in deep boxes called seggars, 
made of a mixture of fire clay and old ground seggars, which 
should be well baked, and capable of sustaining the most in- 
tense degree of heat without being fused. The porcelain 
manufactures of this country labor under a considerable disad- 
vantage in this respect, being unable to procure materials for 
the construction of these cases that will sufiiciently withstand 
the direct heat of the furnace. This difficulty does not occur 
in France, a fact which is assigned by our potters as one prin- 
cipal reason for the better quality of French porcelain. 

A porcelain manufactory was carried on some years since 
at Nungarrow in Wales, but which is now discontinued. The 
wares produced in these works were perhaps superior in quality 
to any porcelain that hitherto has been made in any other part 
of this country. No expense was spared either in the procure- 
ment of materials, or in conducting the various processes ; and 
the want of success on the part of the spirited proprietors is 
referrible solely to the deficiency of public patronage, it being 
found impossible to procure a price for the goods which could 
adequately meet the cost of their manufacture. Since the dis- 
continuance of this establishment, the excellent quality of its 
wares has been more justly estimated, and the prices which 
are now eagerly given by amateurs and collectors for pieces 



56 PORCELAIN MANUFACTURE. CHAP. V. 

of Nungarrow porcelain, are out of all proportion greater than 
were originally demanded by the makers. 

The materials of which this porcelain is composed are of the 
most refractory quality, and it is understood that success in 
their conversion was only attained through the expensive 
measure of sacrificing the seggars employed, which, owing to 
the high degree of heat whereto they were exposed, could 
never be placed a second time in the furnace. 

The office of the seggars is to protect the wares while being 
baked from the direct application of flame and from smoke ; 
the heat is somewhat modified in its transmission through 
them, and applies itself uniformly to each part of the vessels. 
The cases are made of various shapes, sizes, and depths, to suit 
the different pieces they are to contain, and some judgment is 
required in their composition, to fit them for the several kinds 
of pottery. 

To prevent any adhesion of the pieces to the seggars, the 
flat bottom of each is covered with a thin layer of fine white 
sand. That this even may not adhere to the porcelain, the 
Chinese strew over the sand some dry kao-lin in powder. 
Pieces of any considerable size must each be inclosed in a sep- 
arate case, but smaller objects, such as cups or saucers, may be 
placed together to the number of six or twelve, but in no case 
must one piece be placed in or on another in the seggar, and 
all must be so arranged that the heat will be equally applied to 
every part of each. 

In some instances seggars are made having triangular holes 
in their sides, for the purpose of admitting prisms of the same 
form, which are inserted therein, horizontally, in order to sup- 
port a greater number of pieces in a state of isolation within 
each case than could be accomplished by other means. The 
prisms thus used must be compounded of the same materials as 
the cases themselves. This course is not pursued except with 
common articles, and is adopted with the intention of economiz- 
ing the time, space, and fuel employed for baking them. 

If the clay whereof they are composed be well chosen and 
carefully managed, the seggars may be placed from fifteen to 
twenty several times in the furnace before they are rendered 
useless. 

Some art is required so to dispose the cases within the oven, 
with reference to their shape, size, and the objects they con- 
tain, that the heat shall be distributed as faithfully as possible, 
and that the sufficient baking of all the different-sized vessels 
shall be accomplished during the same time. The largest and 
coarsest pieces are usually placed on the floor of the oven, 
which must be previously covered with a layer of sand. If the 



CHAP. V. OF FIRING AND GLAZING. 57 

heat be not faithfully distributed through the whole area 
some pieces would be injured by excessive firing, while others 
would be inadequately baked. The bottoms of the seggars 
being flat, each, as it is placed upon another, forms a cover to 
that beneath, and the entrance of smoke is further prevented 
by placing a ring of soft clay on the upper rim of each case. 
In this manner the seggars are built one upon another, until 
they reach nearly to the top of the oven : the upper seggar in 
each pile is always empty. Each of these piles, as it stands, is 
called a bung ; in building them up, intermediate spaces of 
about three inches must be left for the circulation of heated air 
throughout 

Although the privileges so long enjoyed by the royal manu- 
factory at Sevres, and which were accompanied by correspond- 
ing restrictions placed by the French government upon private 
establishments, must have been upon the whole prejudicial to 
the progress of the art in France, these regulations had yet in 
some respects a contrary tendency. Being secured in a great 
degree from the effects of competition from without, the di- 
rectors of the royal works were enabled to prosecute experi- 
ments with regard to improvements in their utensils and pro- 
cesses, from the adoption of which they might otherwise have 
been deterred by considerations of expense. Suggestions ap- 
pear to have been continually made, having such improve- 
ments for their object, by men who enjoyed the highest scien- 
tific reputations ; and the success of plans thus proposed, con- 
duced to the increasing celebrity of the establishment. 

Among others, MM. de Montigny and Macquer contrived a 
form of furnace, which effected at the time of its adoption a 
very great advantage. In that previously used (and the con- 
struction of which had been copied from those employed in 
Saxony,) the heat was so unequally distributed, that it was 
necessary to vary the composition of the porcelain so as to ren- 
der it suitable to different parts of the furnace. The improve- 
ment here noticed occasioned the sufficient equalization of heat 
throughout its area, and a great inconvenience was at once and 
completely remedied. 

The arrangement whereby this important change was ac- 
complished will be understood by a reference to the following 
figures, which describe the elevation, section, and plan of the 
kiln. The same letters are employed to denote similar parts 
in the different figures. 

A is the interior area of the kiln. This is fourteen feet 
eight inches high, and eight feet three inches in diameter : 
the walls should be three feet thick. BBBB are four air-flues 
placed at equal distances in • the circumference. CCCC are 



58 



PORCELAIN MANUFACTURE, 



CHAP. V. 



hearths one foot below the base of the kiln : the heat from 
these passes towards its centre. DDDD are openings, eigh- 
teen inches square, for the reception of the fuel. These open- 

Fig. 2. 




ings are provided with mouth pieces of plate iron. E is a 
door- way in the side of the kiln: its sill is three feet above the 

Fig. 3. 




ground ; its width is two feet, and its height five feet six 
inches. This door is used for the introduction of the seggars 
within the kiln, after which it must be securely walled up. F 
is a square hole, of which there are three in the entire cir- 
cumference. These are designed for the introduction of trial 
pieces within the kiln : another similar opening is left when 



CHAP. V. 



OF FIRING AND GLAZING. 



59 



walling up the door-way E. The whole of these are provided 
with clay stoppers which exactly fill the holes, and which have 
projections whereby they can be removed or replaced at plea- 
sure. G is the chimney in the centre of the dome-shaped roof; 
it is of a conical form, eighteen inches diameter at the base, less- 
ening to twelve inches at the top. HH represent four air- 




holes, placed over the openings F. These air-holes serve to 
divide the draught, and consequently to equalize the tempera- 
ture of the kiln. I is a round iron plate, supported on four 
pillars of the same metal, and placed over the chimney to de- 
fend the opening. 

When the firing has been sufficiently performed, no more 
fuel is added, and so soon as the smoke from that already upon 
the hearths has passed away, the mouth pieces are entirely 
closed to prevent the passage of air. Shortly after this, the 
chimney G and the air-holes H are also carefully closed, and 
the kiln is left, that the cooling of its contents may go forward 
as slowly as possible. 

Previously to the adoption of this improvement, the kiln em- 
ployed for baking porcelain was always made of a rectangular 
form, having only one fire-place and one air-flue, which stood 
at the side opposite to that whereon the chimney was placed : 
an arrangement which rendered quite inevitable the before- 
mentioned inconvenience, arising from the unequal distribution 
of heat. 



60 PORCELAIN MANUFACTURE. CHAP. V. 

The extension of the art, and the consequent competition 
among the manufacturers in France since the return of peace, 
have compelled them to use the utmost economy in their vari- 
ous processes ; so that, while the quality of their goods has been 
fully sustained, the prices have been importantly lowered. 
These savings have been partly realized through the increased 
skill of the workmen, but are more referrible to the smaller 
proportionate quantity of fuel consumed, which has arisen, not 
from any further improvement in the form of their kilns, but 
through a better arrangement in filling them, whereby they are 
now made to contain, at each baking, nearly one third more of 
pieces than was formerly customary. 

The potter's oven is now always made of a cylindrical form, 
and very similar to the common kilns used for burning tiles, 
with the external appearance of which every one is familiarly 
acquainted. The furnace mouths of the oven are placed at cer- 
tain intervals around it; from these the fire and heated air pass 
into horizontal flues in the floor, and thence ascend through all 
the interstitial spaces between the bungs, until the surplus heat 
escapes through an aperture in the centre of the roof. 

The Chinese subject the greatest part of their porcelain to 
only one firing, drying the pieces sufficiently in the air to pre- 
pare them for glazing. This plan they are able to pursue? be- 
cause the nature of their materials is such as to resist the en- 
trance of water. Their glaze, the composition of which will 
be hereinafter described, is much superior to any used in Euro- 
pean potteries, but requires the most intense degree of heat for 
its fusion, and considerable art is consequently required for the 
management of the fire, as well as in the construction of their 
ovens. These are built in a most substantial manner, so that 
when the fire is at its greatest height, the hand may be applied 
to the outside without any fear of burning. The draft is pn> 
moted by placing the oven at the extreme end of a long narrow 
passage, which acts as a funnel in supplying air for supporting 
combustion, the intensity of which is regulated by four or more 
side apertures, or registers, which are opened or shut according 
as the heat is required to be augmented or moderated. The 
hearth is placed in front, and occupies the whole breadth of the 
oven. The pieces which are placed in seggars, are artfully 
disposed in the oven, in the manner already described as follow- 
ed in England. When the fire is lighted, the furnace door is 
walled up, leaving only an aperture large enough for the intro- 
duction of fuel. The heat is raised gradually during about 
thirty hours, after which time fuel is incessantly supplied by 
two men, who relieve each other at intervals. The wood used 
for this purpose is very carefully dried and cut into slender bil- 



CHAP. V. OF FIRING AND GLAZING. 61 

lets about one foot in length, that their combustion may be ef- 
fected with greater rapidity. 

Great attention is necessary for properly conducting the op- 
eration of baking. Vauquelin observes that the heat must be 
sufficient to expel all the moisture, and occasion the cohesion 
of the parts whereof the paste is composed ; but that, if carried 
too far, the texture of the ware becomes too homogeneal, and it 
is rendered brittle. It requires a degree of heat sufficient to 
melt silver (4717° Fahrenheit) in order to expel the last portion 
of water from clay : when this has been effected, it is found 
that the weight of alumina is diminished forty-six per cent. 

The process of baking usually lasts from forty-eight to fifty 
hours, during which time the heat is gradually increased ; as it 
would be injurious to apply a very high degree at first. In order 
to ascertain when the baking has been carried far enough, the 
oven-man places trial pieces in different parts of the oven, but 
so disposed that they can readily be taken out for examination. 
These pieces are rings made of common Staffordshire fire clay, 
which is found to have the property of changing its color with 
each accession of temperature. By comparing these rings, 
therefore, with pieces of the same clay which have previously 
been sufficiently baked, and which serve as a standard, the ac- 
tual progress of the wares in the oven may at any time be ascer- 
tained precisely, and with less trouble than attends the use of 
Wedgwood's pyrometer. When" the appearance of these trial 
pieces is judged satisfactory, the firing is discontinued, the fur- 
nace and ash-pit doors are closed, and the oven, with its con- 
tents, left to cool gradually during twenty-four or thirty hours. 
It is not necessary to delay the withdrawing of the pieces from 
the oven, until they have become quite cold ; but the sudden 
alteration of temperature would occasion them to crack, if they 
were taken out while their heat was greatly above that of the 
atmosphere. 

Some potters are occasionally tempted, when the furnace 
contains articles of small value, to risk the damage here men- 
tioned, and to withdraw the seggars with their contents with- 
out delay, their object being to profit by the heat of the furnace 
either for introducing a new charge, or for drying a fresh set of 
seggars. No one, however, would be so improvident as to ex- 
pose the finer descriptions of porcelain to this hazard, in order 
to gain any such immaterial advantage. 

From the similarity of its appearance to well-baked ship 
bread, the ware is now called biscuit Its permeability to 
water when in this state fits it for being employed in cooling 
liquids. If previously soaked in water, the gradual evaporation 
from its surface by means of the air, causes an absorption of 

F 



62 PORCELAIN MANUFACTURE. CHAP. V. 

heat from the surrounding atmosphere, which is again supplied 
by neighboring objects, until an equilibrium of temperature is 
restored. 

The proprietors of potteries are accustomed to furnish vases, 
urns, and other pieces of ornamental shapes, in the state of bis- 
cuit, to ladies who exercise their taste and ingenuity in embel- 
lishing them by painting and gilding. Being then returned to 
the manufacturer, the glaze is applied, the baking is finished in 
the gloss oven, and the gilding is burnished by means that will 
be described hereafter. 

If it were attempted to apply the glaze to articles of porcelain 
and earthenware, without their previous conversion into biscuit, 
their texture and shape would be injured by the absorption of 
water from the glaze. Neither would it, for the same reason, 
be possible to ornament the ware by painting, or to transfer pat- 
terns to their surface by printing. There is another reason 
given for the necessity of this previous baking, in the greater 
contractibility of the clay than of the glaze, which would crack 
or peel off if the limit of contraction had not been previously 
attained. It will be remembered that the shrinking of clay 
upon the application of heat is permanent, and that no altera- 
tion of its bulk will occur, unless it be subjected to a still higher 
degree of temperature. By limiting, therefore, the heat of the 
gloss oven in which the baking is finished, below that applied 
to the biscuit, the evil of cracking the glaze, through the con- 
traction of the ware, is avoided. 

The glaze usually employed for common kinds of earthen- 
ware is compounded of litharge of lead and ground flints, in 
the proportion of ten parts by weight of the former to four parts 
of the latter. Cornish granite is sometimes substituted for 
flint, and used in the proportion of eight parts to ten of litharge. 
This method of glazing is objectionable, on account of the injury 
which, notwithstanding every precaution that can be taken, it 
occasions, in its application, to the health of the workmen em- 
ployed, who frequently are seized with paralysis ; and because 
the lead, which is soluble by means of acids, and highly pois- 
onous, renders vessels thus glazed improper for preparing or 
containing many articles of human food. 

The bad effect of raw glazes upon their health, is greatly 
lessened to the workmen when they can be brought to the fre- 
quent use of ablutions. In every pottery the men employed in 
glazing should be, and in most establishments they are, plenti- 
fully supplied with soap, which they are enjoined to use on 
every occasion of quitting their work. Unfortunately, however, 
the workmen themselves have become erroneously impressed 
with a belief in the superior effieacy of ardent spirits in ward- 



CHAP, V. OF FIRING AND GLAZING. 63 

ing off or counteracting the poisonous effects of lead, and fly to 
the use of this as a specific, to a degree which too often proves* 
both physically and morally, worse than the evil which it is in- 
tended to prevent. 

The mixtures just mentioned are called raw glazes ; their 
employment is convenient to the potter because of their cheap- 
ness and extreme fusibility. Flint, which remains unaffected 
in the focus of the most powerful lens, is, when combined with 
lead, melted and vitrified at a comparatively low heat. The 
method of using this glaze is to reduce the ingredients to the 
state of a fine powder, and throw them into as much water as 
will make them of the consistence of thin cream. The mixture 
must be well stirred, that the powders may be always kept uni- 
formly blended throughout the fluid. The pieces are first brush- 
ed to free them from dust, and then merely dipped into the liquid 
and withdrawn, when they must be turned rapidly about in all 
directions, that the glaze may flow equally over the whole sur- 
face. The superfluous liquid having been allowed to drain off 
for a few seconds, and the pieces having been set on a board 
during a few minutes, they are ready for insertion in the seggars. 

Chaptal, in his " Chemistry applied to the Arts," has given a 
process for forming white enamel, which answers well for gla- 
zing the superior kinds of earthenware and tender porcelain. 
Equal parts of lead and tin are kept in fusion until completely 
oxidated. The powder thus formed is ground with water, all 
impurities are removed by repeated washings, and being dried 
it is kept for use. The whitest flints are then chosen, and fused 
with carbonate of potash, the latter being in such proportion to 
the flint, that the mixture will be soluble in water. To the 
solution of flint thus made, muriatic acid must, from time to 
time, be added, until no further precipitation occurs. The 
precipitate thus obtained is pure silex, which, being washed and 
dried, is also fit for use. If then one part of this silex, and one 
part of the metallic oxide, be added to two parts of carbonate of 
potash, and the whole be fused in a crucible, the mass need only 
be reduced to a fine powder to prepare it for use in glazing. 

Mr. John Rose, of the porcelain works at Coalport in Shrop- 
shire, speaks in commendation of a glaze for hard porcelain 
which he has used for some time, and which having been ex- 
amined by competent artists, at the request of the Society of 
Arts, has been reported on very favorably. Mr. Rose's glaze 
is composed of 27 parts of felspar, 18 of borax, 4 of Lynn sand, 
3 of nitre, 3 of soda, and 3 of the China clay of Cornwall. This 
mixture is melted together and ground to a fine powder ; 3 parts 
of calcined borax being added previously to the grinding. 

Glazes for porcelain and the finer kinds of earthenware are 



64 PORCELAIN MANUFACTURE. CHAP. V. 

generally made with white lead, ground flints, ground flint- 
glass, and common salt ; Lynn sand combined with soda, as a 
flux, being frequently added to the ingredients just mentioned. 
Almost every manufacturer uses a peculiar glaze, the recipe 
for which is kept secret by him as much as possible, under the 
idea of its superiority compared with that employed by his 
competitors, so that it is not possible to state proportions with 
accuracy. The French porcelain makers have given the com- 
position of hard glazes made by them, which are all said to be 
formed of flint, ground porcelain, and crystals of calcined gyp- 
sum, in the following different proportions : — 

No. 1. No. 2. No. 3. 
Calcined flint -------8 parts 17 parts 11 parts. 

Ground porcelain - 15 16 18 

Crystals of calcined gypsum - - 9 7 12 

It is necessary to vary the composition of the glaze, in order 
to suit the different materials that form the body of the ware, 
since that would be a very fine glaze for one mixture of earths, 
which would be wholly inappropriate to another, proving defi- 
cient in lustre and being liable to crack. Before adopting any 
glaze in conjunction with a particular kind of ware, it is most 
prudent to make trial of it upon a small scale, in order to prove 
the suitableness of the bodies to each other. 

This branch of the potter's art is greatly indebted to the ex- 
traordinary perseverance of a single man, Bernard de Palissy, 
a native of France, who was born in Agen at the close of the 
fifteenth century. His parents occupying an humble station in 
life, he was entirely indebted to his own unquenchable energy 
and perseverance for the success which crowned his industry. 

The original occupation of Palissy was that of a draughts- 
man, to which pursuit he added land surveying. Accident 
having thrown into his hands an enamelled cup, he was imme- 
diately seized with the desire of improving the art, and thence- 
forward relinquishing all other occupations, gave up his whole 
time, mind, and substance, during several years, to the prosecu- 
tion of experiments on the composition of enamel. He has 
himself given a narrative of his labors, sacrifices, and suffer- 
ings, during the progress of his pursuit, which is intensely in- 
teresting. 

In this account, Palissy represents himself as alternately 
planning and building, demolishing and rebuilding his furnace, 
at every step buoyed up by hope, and as often met, but not sub- 
dued, by disappointment ; the object of remonstrance and de- 
rision to his associates, subject to the expostulations of his wife, 
and witness to the silent but more eloquent reproaches of his 
children. In other respects Palissy proved himself an amiable 



CHAP. V. OP FIRING AND GLAZING. 65 

as well as a highly-gifted man ; for, notwithstanding that his 
efforts were ultimately crowned by success, — that standard 
whereby the judgment of mankind is most easily and therefore 
most usually formed, — one might hesitate to applaud a degree 
of perseverance which, for so long a time, materially interfered 
with the welfare of his family. Amidst all this scene of de- 
privation and disappointment, Palissy bore outwardly a cheer- 
ful countenance, and, throughout the lengthened trial, confined 
within the dungeon of his own breast those feelings of bitter- 
ness which he has so forcibly described as being his portion. 

The extremities to which he was at one time reduced were 
such, that to provide fuel for feeding the furnace, his furniture 
and afterwards even some of the woodwork of his dwelling 
was destroyed ; and in order to silence the clamor of his assist- 
ant workman for the payment of wages, he stripped himself 
of a portion of his apparel. At length, however, these efforts 
were rewarded by complete success ; and fame, honors, and in- 
dependence were thenceforward his attendants through a long 
career of useful occupation. 

Palissy's after pursuits were of a more general character, 
embracing the sciences of agriculture, chemistry, and natural 
history, upon which subjects he both wrote and lectured with 
ability and success. 

Nor did the firmness of his character forsake him for a mo- 
ment to the end of his life. Being a Protestant, and having 
ventured, in some of his lectures, to promulgate facts which 
made against the dogmas of the priests, he was, when in his 
ninetieth year, dragged by the infuriate zeal of these fanatics 
to the Bastile, and died, with consistent firmness, within its 
walls. His heroic reply, while thus imprisoned, to Henry III. 
is above all praise. " My good man," said the king, " if you 
cannot conform yourself on the matter of religion, I shall be 
compelled to leave you in the hands of my enemies." — " Sire," 
replied the intrepid old man, " I was already willing to surren- 
der my life, and could any regret have accompanied the action, 
it must assuredly have vanished upon hearing the great king 
of France say ' I am compelled.' This, sire, is a condition to 
which those who force you to act contrary to your own good 
disposition can never reduce me ; because I am prepared for 
death, and because your whole people have not the power to 
compel a simple potter to bend his knee before images which 
le has made." 

So great is the competition among potters in the present day, 
that means which are injurious to their real quality are fre- 
quently adopted for rendering their wares less costly. Some 
nakers are hence tempted to the employment of materials that 

F2 



66 PORCELAIN MANUFACTURE. CHAPc V. 

will enable them, at a moderate price, to furnish articles appa- 
rently good, but which will speedily prove defective when 
brought into use. The saving which the manufacturer is able 
to effect, through the adoption of an inferior glaze, consists 
not so much in the actual cost of its component parts, as in the 
smaller quantity of fuel required for its vitrification, and in the 
shorter period of time demanded for its conversion. 

The earthenwares offered, at low prices, by hawkers and 
pedlars, and at inferior shops, are mostly composed of clay that 
will not bear a proper degree of heat in the oven, and are 
covered by a glaze so tender as to craze after a few cleansings 
with hot water. If exposed to a high temperature, or if acids 
be applied, the glaze will be dissolved, and the vessels conse- 
quently rendered useless. The quantity of lead which enters 
into the composition of the better kinds of glazes is so small, 
that the deteriorating and pernicious effects which attend upon 
the use of raw glaze need not be apprehended from their em- 
ployment. 

The seggars used to inclose the wares when baked in the 
gloss oven, are similar to those employed in the first firing. 
Previous to their insertion, the pieces must have the glaze 
wiped from the parts which immediately rest upon the bottoms 
of the seggars, otherwise they would adhere and might be bro- 
ken in their removal. The cases are piled up in the manner 
already described, and just that degree of heat must be em- 
ployed which will give perfect fusion to the glaze and cause it 
to spread regularly over the surface. The temperature, of 
course, varies according to the quality of the articles and the 
composition of the glaze ; but, for the reason already stated, it 
must never be carried beyond the degree to which the biscuit 
has been previously exposed. In practice, the temperature of 
the gloss oven is generally less by about ten degrees of Wedg- 
wood, or 1300 degrees of Fahrenheit's scale, than the heat of 
the biscuit oven. 

As alkaline substances are so powerfully instrumental in 
promoting the fusion of intractable bodies, it may be thought, 
that by increasing their proportion when combined with fel- 
spar, glazes might be formed that would fuse at a heat suffi- 
ciently moderate for any description of earthenware, and that, 
consequently, the use of oxide of lead, which is so pernicious, 
might be altogether abandoned : but another serious evil which 
would then be experienced prevents this substitution. The 
glaze, if it contained beyond a certain portion of alkali, would 
not undergo the same degree of expansion by heat as the body 
whereon it is laid, and would, as a consequence, crack to such 
a degree as, when brought into use, would allow any greasy 



CHAP. V. OP FIRE AND GLAZING. 67 

matter to penetrate through to the body of the ware ; and this 
would speedily destroy its coherency. 

The qualities which it is the object of the manufacturer to 
give to porcelain of the finest description, are density, white- 
ness, transparency, and fine texture of the glaze. These prop- 
erties are estimated in the order wherein they are here enume- 
rated, compactness of body being the point which it is considered 
most desirable to attain. The glaze, as seen in the finished 
porcelain, should not put on a lustrous appearance ; but while 
beautifully smooth to the touch, should present to the eye rather 
the softness of velvet than the gloss of satin. This peculiar 
semblance will only be produced with glaze that melts with 
difficulty, and when the heat has been raised precisely to, and 
not beyond, the point that is necessary for its fusion. 

Stoneware is a very perfect kind of pottery, and approaches 
nearer than any other description to the character of porcelain. 
Its body is exceedingly dense and compact, so much so, indeed, 
that although vessels formed of it are usually glazed, this cov- 
ering is given to them more with the view of imparting an at- 
tractive appearance than of preserving them from the action of 
liquids. When properly made and baked, stoneware is suffi- 
ciently hard to strike fire from flint, and is as durable as por- 
celain. 

This kind of earthenware is composed of clay and flint. The 
proportion in which these ingredients are used is said to vary 
in different manufactories, and it is difficult to ascertain the 
precise quantities employed in any. The grinding and dilution 
of the materials is effected in the manner already described, 
and when these have separately been thus treated, their union 
is commonly effected in the proportion of about eighteen mea- 
sures of argillaceous to fourteen measures of siliceous fluid. 
Any larger proportion of flint would render the compound more 
difficult to be worked ; and if much less were used, the baked 
ware would not present a sufficiently smooth and shining ap- 
pearance. 

The best descriptions of this ware have very long been made 
in the potteries at Lambeth, the proprietors of which procure 
their supply of clay from Devonshire and Dorsetshire, and pur- 
chase flint already ground from Staffordshire, where this ma- 
terial can be afforded at a cheaper rate than would attend its 
preparation so near the metropolis. 

The plan introduced by the two brothers Elers is still pur- 
sued, of glazing these goods by the decomposition of common 
salt thrown into the kiln, at or near the conclusion of the baking 
process. Other glazes are likewise employed for many articles, 
and, according to the usual system, the particular components of 



68 PORCELAIN MANUFACTURE. CHAP. VI. 

these are also veiled in mystery ; ground glass is, however, 
understood to be the basis of all. 

One of the most considerable of the Lambeth potters has re- 
cently announced the discovery of a glazing compound, which 
is sufficiently fusible without containing a particle of lead, and 
which has been proved capable of altogether resisting the ac- 
tion of acids ; it is used by him for coating the insides of jars 
and bottles of all descriptions. 

The different colors observable on the outer surface of drink- 
ing jugs and other articles, are owing to the partial use of a 
glaze, the part to which this is applied becoming dark in the 
heat of the kiln, while the glazing of the light colored portion 
is caused, as before mentioned, by the introduction of salt. 

The fashioning of stoneware pottery is in all respects con- 
ducted similarly to the processes already fully described. Seg- 
gars are mostly employed for inclosing the pieces during the 
baking, which usually occupies about forty-eight hours. 

Vessels of considerable size, some being capable of containing 
sixty imperial gallons, are made in this manner, and are found 
highly useful in performing many chemical operations con- 
nected with the arts.. 



CHAP. VI. 

ON THE ART OF APPLYING COLORS AND ENGRAVINGS TO 
EARTHENWARE. 

Antiquity of Enamel Coloring. — Specimens from Ancient Egypt. — From the 
Royal Works at Sevres.-Painted Ware of Worcester— Of Staffordshire — 
Of Derby— Of Yorkshire. — Great Services of Mr. Wedgwood in this Branch 
of the Manufacture. — Mystery in the Preparation of Colors. — Publication 
of Processes by M. Brongniart. — Metallic Oxides — Addition of Fluxing 
Bodies necessary— And why.— Colors Employed for tender and for hard 
Porcelain. — Vehicle used with the Colors. — Mode of their Combination. — 
Description of Colors — Purple and Violet. — Red. — Yellow. — Blue. — Green. 
—Brown. — Black.— White.— Compound Colors.— Precautions necessary in 
Forming those Compounds. — Gilding. — Lustreware. — Preparation of Col- 
ors. — Enamelling Kilns. — Trial Pieces. — Method of Gilding and Burnish- 
ing.— Copperplate Engravings. — Mode of Transferring Impressions to 
Earthenwares. — How Performed in France. 

The art of painting on earthenware, although of compara- 
tively recent introduction into England, is by no means a 
modern invention. It is well known that the ancients manu- 
factured colored enamels ; and some specimens of the art, per- 
formed by the Egyptians more than three thousand years ago, 
have been preserved to the present day, which is an evidence 
of this fact ; showing us, at the same time, that, in so remote an 



CHAP. VI. APPLYING COLORS AND ENGRAVINGS. 69 

age, the artists of Egypt were possessed of sufficient practical 
knowledge of chemistry, to avail themselves of processes which 
have been brought to light anew by scientific investigators of 
more modern times. 

Recently, the art has been carried to an admirable degree of 
perfection in Europe. Some specimens are preserved in the 
porcelain works at Sevres, of which the French artists are 
justly proud ; while the performances in our own potteries at 
Worcester, in Staffordshire, at Derby, and yet more recently 
in Yorkshire, are such as entitle them to be placed in an equal 
rank with those of our continental neighbors. 

When, about seventy years ago, Mr. Wedgwood commenced 
the series of improvements, by which his name has been ren- 
dered so deservedly celebrated throughout Europe, no attempts 
at embellishment had been made in the English potteries ; and 
if ornamented services of porcelain were seen on the tables of 
the wealthy, they were always of foreign, and generally of 
oriental production. So soon, however, as, by the intrinsic 
merit of his wares, this enterprising manufacturer had secured 
not only the patronage of royalty, but the more solid support of 
his countrymen in general, he called into action the crucible of 
the chemist, and the pencil of the artist, and led the way in 
bestowing that degree of outward embellishment on his pro- 
ductions, which converted them into objects of elegance, and at 
once encouraged and gratified the growing taste for luxury 
among the higher classes in this country. 

The system of mystery still preserved in the English pot- 
teries, in all that respects the composition and glazing of wares, 
was likewise long practised with regard to the preparation of 
colors. If, at any time, a manufacturer had found out a prepa- 
ration more advantageous than that in use before, he always 
endeavored to limit the benefit of the discovery to his own 
works ; a desire more easy of accomplishment formerly than it 
has become since the more general diffusion of the light of 
science. M. Brongniart, at one time director of the national 
manufactory of porcelain at Sevres in France, has the merit of 
being the first who published a correct statement of the most 
approved plans for preparing and combining the metallic oxides 
used in coloring porcelain and glass. The employment of these 
substances for such purposes had been long before and com- 
monly practised, and the art was even carried by some of its 
professors to a high degree of perfection ; but, as M. Brongniart 
observes, no attempt had been made at the time his essay was 
written (1801), to apply to it the principles of chemical science ; 
and such pretended descriptions as had then been published 
ontained no theory, and consequently no general principles. 



70 PORCELAIN MANUFACTURE. CHAP. VI. 

Where even the authors did offer explanations, these were 
founded upon the most ridiculous hypotheses ; so that all im- 
provements were rather the offspring of chance than the result 
of systematic inquiry. 

It would afford but little satisfaction, or information, to relate 
by what steps the art now under consideration was reduced 
into a system, and thus became, in some measure, deserving of 
the name of a science. It will be sufficient to state the means 
by which that art is now rendered available in the best con- 
ducted porcelain works. In a great part of the following de- 
scription, ^he lucid statements given by M. Brongniart in his 
essay will be closely followed ; since, with scarcely any varia- 
tion, the same processes have been used in both the French 
and English establishments to the present day. 

In this branch of the art there are various objects to be con- 
sidered, a proper acquaintance with which is necessary to suc- 
cess. Such are, the composition of colors ; the fluxes which 
are necessary to render these fusible, which unite them to the 
wares, and in many cases impart brilliancy to their tints ; the 
vehicle employed in laying on the colors, and the course to be 
pursued in fixing them on the porcelain by means of heat. 

Metallic oxides form the bases of all vitrifiable colors, but 
every metallic oxide is not proper for being employed in deco- 
rating porcelain. Some are highly volatile, as the oxides of 
mercury and of arsenic. Others part so freely with the oxygen 
they hold in combination, that their color proves uncertain, and 
varies with every application of heat ; such are the puce-colored 
and red oxides of lead, and the yellow oxide of gold. Oxides 
which are susceptible of great variations are very seldom em- 
ployed. Black oxide of iron is not used alone for producing 
that color on porcelain ; and the green oxide of copper, as for- 
merly prepared, was so uncertain that it was very rarely em- 
ployed ; but this evil has, since the time of M. Brongniart, 
been greatly remedied. 

Oxides uncombined with other substances are not susceptible 
of fusion ; and although they may be attached in thin strata to 
vitrifiable bodies by a very violent heat, yet their colors, with 
the exception of lead and bismuth, would, in such case, become 
dull, and possibly be even destroyed. In order to promote their 
fusion, a flux is therefore added, the composition of which varies 
according to the means employed for diluting the colors at the 
time they are used. Where a volatile oil is chosen for this di- 
lution, a flux composed of glass, nitre, and borax is most proper ; 
but when, as in the Sevres manufactory, gum-water is substi- 
tuted for this volatile oil, the flux must be varied, because borax 
cannot be properly diluted in gum- water. A compound of glass^ 



CHAP. VI. APPLYING COLORS AND ENGRAVINGS- 71 

lead, and silex is therefore preferred by M. Brongniart, who, 
however, has given no directions regarding the proportions 
wherein these bodies must be brought together. The other 
menstruum, which is recommended by M. de Montamy, in his 
treatise on painting in enamel, is composed of 
Powdered glass 40 parts. 
Calcined borax * 22 
Refined nitre - 44 
It is indispensable, not only that the borax and nitre be as pure 
as they can be rendered, but also that the glass shall not con- 
tain the smallest particle of lead in its composition. These in- 
gredients must first be well triturated together in a glass mor- 
tar, with a pestle of the same material, during an hour, and 
then exposed in a crucible to the heat of a charcoal fire, until 
the swelling, which for a time accompanies the fusion of the 
mass, has ceased. 

By means of this flux the colors are fixed upon the porce- 
lain, and made to assume a resplendent appearance : the metallic 
oxides, being enveloped by the flux, are preserved from all con- 
tact with the air, and their color is rendered permanent ; the 
fusion having been promoted at a temperature too low for their 
destruction. • 

Trial should be made of the habitudes of different colors in 
combination with their flux, in order to determine the exact 
quantity to be employed with each. Various substances vitrify 
with greater or less facility when thus combined, and the 
greatest carefulness and skill are consequently required, so to 
proportion the relative quantities of each, that not more of the 
flux shall be added than is necessary to cause a perfect vitrifi- 
cation. If too little were used, the colors, although they might 
attach themselves to the porcelain, would nevertheless be dull ; 
and if too much, the colors would run, their outlines would not 
be sufficiently decided, and all the finer touches of the artist 
would disappear. It has been remarked, that colors which re- 
quire for their fusion more than six times their weight of flux, 
do not flow with sufficient facility ; and, as they cannot be ap- 
plied with a pencil, so as to produce a satisfactory result, should 
be rejected. 

Such metallic oxides as would have their colors altered by a 
strong or often repeated heat, are employed after being mixed 
with their flux, but without having been previously fused with 
it. In many cases metallic oxides are first fused with the 
requisite proportion of their flux, and are then ground for use. 

* Mr. Tilloch remarks (Philos. Mag. vol. li.) that borax should be used 
sparingly, as it causes efflorescence, and promotes the decay of the enamel 
colors. 



72 PORCELAIN MANUFACTURE. CHAP. VI. 

Enamel is glass made opaque by the oxide of tin, and ren- 
dered fusible by the oxide of lead. All glazes that contain lead 
participate in the properties of enamel. Raw glazes used for 
covering tender porcelain are of this nature. The colors em- 
ployed in painting this porcelain are those which serve for 
painting in enamel ; they require less flux than others, because 
the surface to which they are applied becomes soft enough to 
be penetrated by them. Hard porcelain, whose nature is iden- 
tical with those of China and Saxony, has two kinds of colors 
applied to it. Those of the first kind, which are used in the 
representation of different objects, are baked in a heat much 
below that necessary for baking porcelain ; while the other 
colors,* which are few in number, must be exposed to the highest 
degree required by the porcelain itself. The glaze used for 
hard porcelain has little or no lead in its composition. The 
Sevres manufacturers, and some few in England, employ fel- 
spar without any mixture of lead. This glaze, when exposed 
to the heat of the gloss oven, dilates, and its pores are opened 
without becoming soft, so that the colors are not absorbed by it, 
and do not undergo those changes which occur when they are 
applied to tender porcelain, where, by mixing with the body of 
the enamel, they become faint and indisfmct. This effect is 
much increased likewise where some particular colors are em- 
ployed, and especially the reds produced from iron, which are 
exposed to the destructive action of the oxide of lead that is 
contained in the glaze. Painting on tender porcelain must, for 
these reasons, be several times retouched with the pencil, in 
order to give to it the distinctness and brilliancy which follow 
the use of the same colors on hard porcelain, so that a high de- 
gree of ornament is seldom or never given to any but the latter 
description. In the embellishment of hard porcelain, these re- 
touchings are not required, except for the most elaborate speci- 
mens of the art, which can by such means, however, be pro- 
duced with the most admirable degree of perfection, so as to 
render paintings on porcelain not distinguishable from the 
finest productions of the pictorial art, without reference to the 
body upon which it is performed, or to the means used for 
bringing out the colors ; natural objects, landscapes, portraits, 
and even historical pieces being represented with all the truth, 
as well as with all the brilliancy of coloring, which distinguish 
the works of the first masters. 

One great inconvenience attends the repeated exposure to 
the heat of the oven of pieces thus retouched ; the colors being 
liable to peel off, unless the greatest care has been used in their 
application. This defect has been remedied in the Sevres 
works, by introducing a calcareous flux into the felspar glaze, 



CHAP. VI. APPLYING COLORS AND ENGRAVINGS. 73 

which softens it, without at all affecting* the body of the ware. 
Soda and potash are never used as fluxes, as their introduction 
causes the colors to scale ; the reason for which is, that, becom- 
ing volatile in a great heat, they abandon the color, which then 
will not adhere to the glaze. 

The liquid matter which serves as a vehicle in laying on the 
colors, is rubbed with them upon a glass palette until the whole 
is intimately united. The mixture must be brought to that 
state of dilution which is most proper and convenient for its 
application with a hair pencil on the surface of the porcelain. 
Great care is used in the choice and management of these dilu- 
ent liquids, which must always be sufficiently volatile to be en- 
tirely dissipated in the heat to which the wares are afterwards 
exposed. In France, the preference is given to oil of lavender 
as a vehicle ; and in order to insure the proper degree of fluid- 
ity, this oil is divided by distillation into two parts : that which 
first comes over, being the most volatile, and having the least 
density, is used for diluting the colors when they become too 
thick ; and, on the other hand, the portion that remains in the 
retort, having the opposite qualities, is reserved for thickening 
them when they run too freely. Oil of turpentine, which has 
been some time in store, is more generally used in England, 
and is said to answer the purpose better than any other volatile 
fluid. 

It was remarked by Brongniart, whose practical knowledge 
qualified him to judge correctly on the subject, that of all the 
processes for painting on glass and porcelain described in works 
that were in existence at the time his essay was published, 
there was not one, by strictly following which, the desired co- 
lors could be produced. In describing these processes, one au- 
thor had followed another without knowledge or examination ; 
and even the treatise by Leviel, which forms part of the volu- 
minous work on arts and manufactures, published under the 
auspices of the Academy of Sciences in Paris, is not free from 
this reproach. Such want of correctness, from whatever cause 
it may have arisen, is little honorable to the authors, who if 
even unable, by penetrating the veil of mystery wherein the 
manufacturers shrouded their practices, to expose them correct- 
ly to the world, might, without difficulty, have ascertained the 
truth or falsehood of that to which they were affixing the stamp 
of their authority. The course which they pursued would as- 
suredly fail of success in the present day, when an acquaintance 
with chemical phenomena is no longer confined, as it formerly 
was, to a few among the rarer order of students, and such er- 
rors would be certain of confutation at the moment of their pro- 
mulgation. 

G 



74 PORCELAIN MANUFACTURE. CHAP. VI. 

Purple and violet colors are procured by dissolving gold in 
aqua regia (nitro-muriatic acid), and immersing a bar of pure tin 
in the solution. The product thus obtained is called, from its in- 
ventor, the purple precipitate of Cassius, and is used very gen- 
erally for giving the above-mentioned colors to porcelain. A 
preferable way of preparing this precipitate is to dissolve the 
two metals separately, and by then bringing the solutions to- 
gether in different proportions, various shades of carmine, vio- 
let, and purple are obtained. The first of these three tints is 
seldom used in porcelain works, for although extremely beauti- 
ful, it is also very transient, and may be easily spoilt by a small 
excess of heat, or by the contact of carbonaceous vapors, a cir- 
cumstance which is the less important, as its place may be well 
supplied by a rose color obtained from iron, and which is not 
liable to the same disadvantage. Carmine color, when used for 
tender porcelain, is prepared with fulminating gold (made by 
dissolving the metal with aqua regia and precipitating with am- 
monia), and muriate of silver. This compound is without any 
addition of tin, which shows that an union of the oxide of tin 
with that of gold is not necessary— as many have supposed — 
for the production of purple. 

Violet color is also made with the purple oxide of gold, re- 
quiring the presence of some portion of lead in the flux for the 
development of this shade. These three colors cannot bear 
exposure to the full heat of a porcelain furnace, in which they 
would wholly disappear. In using the precipitate of gold, it is 
mixed with about six times its own weight of flux, and is em- 
ployed without previously fusing the two bodies together. 
When first applied on the porcelain, it is of a dirty violet color, 
but by exposure to heat this passes to a most beautiful purple. 
It is recommended to employ charcoal as fuel in baking this 
color. Frequent exposure to the fire will materially impair its 
beauty. 

Red oxide of iron, prepared by the united action of fire and 
nitric acid (the aquafortis of commerce) yields a red color, 
which, although beautiful, is less brilliant than that produced 
from gold. As already stated, it is, however, preferable on ac- 
count of its less liability to change. Shades of red, deepening 
from rose color, and passing by the increased application of 
heat to brown, are obtained from iron. The flux employed with 
this oxide is composed of vitrified borax, sand, and a small pro- 
portion of red lead, and the color may be used either with or 
without previous fusion with its flux. By the mixture of black 
and red oxides of iron, in different proportions, various shades 
of reddish brown, chestnut, &c. are obtained. Red colors pro- 
duced from iron cannot be used on tender porcelain, since they 



CHAP. VI. APPLYING COLORS AND ENGRAVINGS. 75 

disappear, in that case, on exposure to heat. This effect must 
be ascribed to the presence of lead in the glaze. Several ex- 
periments, conducted by M. Brongniart, have proved this fact 
beyond all controversy. 

A very permanent red color is procured by calcining the ox- 
ide of iron with double its own weight of common salt (chlo- 
ride of sodium). The processes used for this purpose must be 
carefully conducted, and the salt purified and decrepitated — 
that is, subjected to the action of heat until all crackling 
noise has ceased. The oxide is procured by dissolving iron 
filings in nitric acid, and precipitating with salt of tartar (sub- 
carbonate of potass). The precipitate must then be placed on 
a thin sheet of iron, and exposed under a muffle to the heat of 
a charcoal fire, until it has taken a fine red color. The two 
substances having been well triturated together in a glass or 
porcelain mortar, are then calcined in a crucible, and the oper- 
ation should be carried as far as possible, without occasioning 
the vitrification of the mass. When taken from the fire and 
cooled, the compound is again triturated ; successive portions 
of hot water are poured upon it, stirred, and then removed, 
until the water is no longer colored. The fluid thus tinged 
is allowed to settle, and is, when clear, poured from the sedi- 
ment, which is then washed five or six times in fresh portions 
of clear water. 

To obtain yellow colors, for both hard and tender porcelain, 
white oxide of antimony, mixed with sand and oxide of lead, 
are employed, the latter substance serving as a flux to the 
others. . Great carefulness is required in the preparation, as the 
lead frequently approaches, by reason of the heat, to a metallic 
state, and, in that case, appears in the form of black spots on 
the wares. Oxide of tin is sometimes added, and when the co- 
lor is required to be livelier, and approaching to that of saffron, 
red oxide of iron is added, the too great redness of this being 
subdued by the action of the lead, in the fusion which the ingre- 
dients undergo, previous to their application on the porcelain. 
The colors thus produced are not susceptible of change, but if 
exposed to the full heat of a porcelain furnace would be en- 
tirely dissipated. 

Oxide of uranium, mixed with oxide of lead, produces a 
straw color. By decomposing chromate of potass, with nitrate 
of lead, which is a saturated solution of lead in nitric acid, chro- 
mate of lead is precipitated, and this proves a very excellent 
yellow color. 

Naples yellow is composed of 24 parts of ceruse, 4 parts of 
oxide of antimony, and one part each of alum and sal ammoniac 
(muriate of ammonia), calcined together' at a moderate heat 



76 PORCELAIN MANUFACTURE. CHAP. VI. 

during three hours. The shade is varied by increasing or di- 
minishing the proportion of sal ammoniac. The quantity of flux 
that must be combined with this color for use is uncertain, and 
must be matter for experiment with the manufacturer. 

For the production of blue, well prepared and very pure 
oxide of cobalt is employed, mixed with a flux. Oxides of tin 
and of zinc, added in different proportions, give different 
shades, from a deep rich color to a light blue. As the oxide of 
cobalt is volatilized at a high heat, it is impossible to place in 
the same case, white pieces, and such as are painted blue ; 
since the former would certainly assume a bluish tint in the 
operation of baking. This difficulty does not occur with tender 
porcelain, on which the cobalt is not volatilized as in the other 
case, owing to the heat being very inferior to that used in ba- 
king hard porcelain. These blue colors, if they have been pre- 
viously fused, do not change at all after their application. The 
rich smalt, known under the name of azure-blue, is only the 
glass of cobalt, mixed with sand. This color must be fused in 
a crucible, and reduced to an impalpable powder in an agate 
mortar, after which it may be used in combination with flux. 

Prussian blue, which results from the union of hydrocyanic 
acid with oxide of iron, is very extensively used in the arts ; 
and being prepared on a large scale for sale, in various parts of 
the kingdom, no manufacturer of porcelain will undergo the 
trouble, or encounter the unpleasant circumstances attendant 
upon its preparation, but will rather obtain the comparatively 
small quantity he may require by purchase. 

Green oxide of copper is usually employed for the production 
of a green color. On precipitating in different vessels, by means 
of potass, solutions of copper which are equally pure and con- 
centrated, it is perceptible that the precipitate is formed more 
quickly in some vessels than in others ; and if these different 
products are separately collected, those which are most prompt- 
ly formed are, when dried, of a fine bright green, and produce 
a corresponding color on porcelain; while those precipitates 
which are deposited more slowly, form earthy and less dense 
particles of a much darker hue, and which, when applied to por- 
celain, yield a less pleasing color, and pass sometimes to black 
during the baking. If, however, the precipitated oxide is pre- 
viously fused with its flux, this change need not be apprehend- 
ed. Very pure oxide of copper is frequently procured by pla- 
cing sheets of the metal in the oven wherein the ware is glazed. 
Mixtures of yellow and blue are sometimes used in the compo- 
sition of green colors : some of these will not exist in the heat 
of a porcelain furnace. Various shades of beautiful green may 
be obtained, by mixing, in different proportions, Prussian blue 



CHAP. VI. APPLYING COLORS AND ENGRAVINGS. 77 

with the chromate of lead already described. A mixture of the 
oxides of cobalt and nickel, will resist a very intense heat, but 
does not produce a genuine green : it is rather an olive color. 

Oxide of chromium gives a beautiful green color, which is 
indestructible in the heat of a porcelain furnace. That class of 
green colors, called celestial blues, can only be applied, accord- 
ing to Brongniart, on tender wares : being partly composed of 
potass, they scale off from hard porcelain. 

Different shades of light and of deep rich brown are obtained 
from mixtures of the oxides of iron. These must be fused 
with thin flux before they are used, after which fusion they do 
not undergo any change on the application of heat. Russet 
grounds, known under the designation of tortoise-shell, are pro- 
duced in this manner. Felspar is employed as a flux with these 
colors. 

There is not any metallic oxide which alone will give a good 
black. Oxide of manganese approaches the nearest to it. The 
black oxide of iron yields a very dull color, which sometimes 
changes to red. The color-makers therefore unite several ox- 
ides together, and thence obtain a very beautiful black. The 
oxides thus combined are of manganese, the brown oxide of 
copper, and a small proportion of the oxide of cobalt A gray 
color is obtained by omitting the copper, and increasing the 
proportionate quantity of the flux. 

Cobalt, oxide of copper, and umber, in equal parts, reduced 
together to an impalpable powder in an agate mortar, prove a 
very good black. This must be used with three times its 
weight of flux. Another black is composed of four parts oxide 
of copper, one part of smalt, and one part of black oxide of iron, 
which, like the former compound, must be rubbed together to a 
fine powder, and used with three parts of flux. 

In the " Annales de Chimie et de Physique," (Vol. 20. 1822), 
directions are given for the preparation of a beautiful black en- 
amel, the verification of which on the part of our porcelain 
manufacturers is perhaps desirable. The experiment necessary 
for this purpose might have been somewhat simplified, if the 
artist by whom the directions are communicated had stated the 
proportions wherein the ingredients should be brought together. 
The formula directs that chloride of platina, dissolved in water, 
should be mixed with nitrate of mercury. By then subjecting 
the precipitate which will be formed to a heat just sufficient to 
volatilize the proto- chloride of mercury, a black powder will be 
obtained. This is the enamel, which must be applied in the 
usual manner, in combination with a fluxing material. 

M. de Montamy in his treatise, to which allusion has already 
been mrtde, gives a recipe for composing a pure white color, 

G2 



78 PORCELAIN MANUFACTURE. CHAP. VI. 

which is found very serviceable by the French artists in form- 
ing their series of shades, as well as in the composition of those 
parts of their designs which require to be represented in a bril- 
liant white. This color is composed of one part of virgin tin, 
and two parts of common salt. The latter must be thoroughly 
purified, by first dissolving it in distilled water, then filtering 
the solution through paper, and afterwards evaporating it to 
dryness over the fire in a porcelain capsule. The salt, which is, 
by this means, made extremely white, must be further exposed 
to heat in a crucible, until all decrepitating noise has ceased. 
The purification will be yet more perfect, if, after filtering it, 
the solution is partially evaporated, and then placed in a cool 
situation to crystallize slowly. Those artists who are the most 
particular in their processes, select preferably from the rest 
such crystals as take the form of cubes. The next part of the 
process is to place a crucible on the fire, well covered, to pre- 
vent the entrance of smoke or ashes. When this crucible is at 
a red heat, the tin is introduced, and is left until it is not only 
fused, but red-hot, at which time the purified salt is added in 
the proportion already mentioned. Taking then a clean iron 
spatula, the end of which must be previously heated, the mix- 
ture is stirred until the substances are well incorporated to- 
gether. The crucible being then again covered, is to be sur- 
rounded with burning charcoal, and from time to time, the 
spatula, which must be always perfectly clean and hot, should 
be introduced to agitate the mass. When the end of this spat- 
ula, in being tempered by the heat of the crucible, begins to grow 
white, it is a sign that the calcination is carried sufficiently far, 
and that the crucible should be removed from the fire ; the cal- 
cination usually occupies an hour for its completion. The com- 
pound should next be bruised in a mortar of glass or of agate, 
and again placed in a crucible which is set in the midst of 
burning coals and covered with a muffle. The heat is then 
raised gradually, and continued during three hours, when, on 
removing the crucible from the fire, the color is found to be 
hard, and requires some force to detach it from the vessel. 
This done, it must be pounded in a mortar, and washed in hot 
water that has been filtered or distilled, and fresh portions of 
water added, until the fluid has no longer any taste of- salt. 
The white color is afterwards to be boiled violently with an 
abundance of water in an earthenware vessel for two hours, 
supplying hot water during that time to replace the portion that 
is evaporated. When the supernatant water has become clear 
by standing, it must be poured off carefully. 

This white may be advantageously employed in painting with 
oil, as it mixes well with it. When used on porcelain, it must 



CHAP. VI. APPLYING COLORS AND ENGRAVINGS. 79 

be mixed with three times its weight of flux. The preparation 
of this color will not succeed unless the tin is extremely pure, 
and it is essential that the nicest possible degree of cleanliness 
should be observed throughout the operations. 

By making different mixtures of the various colors here de- 
scribed, every hue that can be desired may be obtained. It is 
not, however, so easy, as without due consideration it might 
appear, to produce these various shades. Great judgment in 
the selection of materials, carefulness in their preparation, and 
knowledge as to the relative proportions wherein they should be 
brought together, are essential to success ; and an acquaintance 
with the science of chemistry is highly desirable. There are 
some colors which, if mixed, would mutually destroy each other, 
and on the exposure of metallic oxides to heat, changes ensue, 
which result not from the nature and habitudes of the colors 
themselves, but rather from the influence of the bodies to which 
they are applied. 

It would be scarcely possible to treat satisfactorily upon the 
inciting causes of all these variations, a full knowledge of which 
can result alone from the practical experience of the artist and 
manufacturer. 

Many potters do not prepare their own enamel colors, but 
3urchase what they require from persons who manufacture thern 
or sale. Some of these preparations are exceeding costly, and 
as the temptation to adulterate them is consequently great, the 
x)tter should have good reason to rely on the probity of the 
color-maker with whom he deals. A fraudulent mixture, the 
detection of which would be impossible before its use,, except 
Dy means of a chemical analysis, might be the occasion, in its 
results, of severe loss and disappointment. With the exception- 
of the great works at Sevres, this system of purchasing their 
enamel colors has, for many years past, been very general among 
the potters of France. In a report made to the French govern- 
ment, by a commission appointed in 1819, to examine into the 
progress of manufacturing industry in that country, occasion 
was taken for offering congratulations upon this establishment 
of an independent occupation, as marking the great extension 
of the porcelain manufacture, and as offering to the artist 
means of obtaining every shade of color, prepared by persons 
whose interest is involved in ascertaining their effects when 
ubmitted to the heat of the furnace, thus removing all uncer- 
tainty from the operations of the painter, and rendering it un- 
necessary for him to suspend his work that he may prepare his 
olors. 

The gold used in gilding porcelain is applied in a metallic 
*tate. To prepare it for this purpose, it is dissolved in aqua 



80 PORCELAIN MANUFACTURE. CHAP. VI* 

regia, and the acid being afterwards dissipated by the applica- 
tion of heat, the gold remains in the state of powder at the bot- 
tom of the vessel. This powder must be mixed with borax 
and gum-water, as a vehicle for causing it to flow from the 
pencil and fix upon the wares ; which being then baked, the 
gilding appears void of lustre, and requires to be afterwards 
burnished with either agate or blood-stone. 

Gold and silver lustre-ware is commonly of an inferior quality. 
The metallic oxides used for covering these vessels are inti- 
mately mixed with some essential oil, and then brushed entirely 
over their surfaces. The heat of the enamelling oven, which 
dissipates the oxygen, restores the oxides to their metallic state, 
but with some diminution of brilliancy. The oxide of plati- 
num is used for making silver-lustre. 

Colors, when they are required for use, should be first 
pounded quickly in a mortar made of either agate, porcelain, or 
glass, with a pestle of the same material, and covered to pre- 
vent the access of dust. They must be afterwards ground on a 
glazed palette, firmly bedded in plaster on a wooden frame, and 
perfectly level. The artist who decorates porcelain is required 
to rub his colors with as much nicety as is used by miniature 
painters, so that there must not remain the least perceptible 
roughness, either under the muller or between the fingers. The 
requisite proportions of volatile oil and of flux are added and 
ground with the colors on the palette, the whole having been 
carefully weighed before their union. The general rule is to 
put five parts of flux to two parts of coloring matter : but some 
colors, #s already mentioned, require more, while with others 
this proportion would be too great. Smalt requires to have 
combined with it only half the sum of its own weight. 

The artist must be attentive to grind his colors with the 
smallest quantity of oil that will suffice ; if this should be in ex- 
cess, it may in evaporating leave spaces between the particles 
of color, and the subject would appear very imperfectly exe- 
cuted. The fluidity of the mixture should be kept at that ex- 
act point which enables the artist to produce the finest strokes 
with clearness and facility. 

Before the pieces which have been painted are baked in the 
enamelling-kiln, it is necessary to dry the colors by evaporating 
the oil used with them as the vehicle. 

Every considerable pottery has enamelling-kilns of various 
sizes. These are in form like a chemist's muffle, from about 
six to ten feet long, and from three to five feet wide. The ar- 
ticles are piled in the kiln until it is filled, when the mouth be- 
ing closed, fire is applied, and continued for about eight or ten 
hours, at the end of which time the colors are found to be burnt 



CHAP. VI. APPLYING COLORS AND ENGRAVINGS. 81 

into the glaze. In piling the pieces in the kiln, care must be 
used to avoid the placing of any one piece upon the gilt border 
of another. The muffle is provided with trial pieces, which 
can be extracted from time to time during the baking, and 
which will indicate the general state of the contents of the kiln, 
so as to govern the continuance of the operation. No delay 
should occur between the sufficient baking of the colors, and 
the withdrawing of the fire, as their brilliancy would be injured 
by its longer continuance. The contents of the kiln are left 
undisturbed until they are cool, and are then withdrawn. All 
impure exhalations are prejudicial to the beauty of colors, and 
every substance whence they can arise should,- as far as possi- 
ble, be kept away from the kiln during the process. ~ 
Gilding on porcelain or on glass is performed either with or 
without the addition of a fluxing material, the gold being made 
to adhere to the surface by the incipient fusion of either the 
glazing on the porcelain, or of the surface of the glass, or of the 
flux employed. 

Gold is used for this purpose sometimes in the form of leaf 
gold, and at other times in that of powder, prepared either me- 
chanically, or by chemical precipitation. When the first of 
these two methods is employed, leaf gold must be ground with 
honey or with gum-water of an equal consistence ; the honey 
or gum being afterwards washed away, the gold may be kept 
for use in paper or in shells, and the use of these latter recipi- 
ents has occasioned this powder to be known among artists as 
" shell gold." This precious metal is precipitated from its solu- 
tion in aqua regia, by adding to it a watery dilution of green vit- 
riol (proto-sulphate of iron) or strips of metallic copper. Gold 
powder may likewise be obtained from the same solution by dis- 
tilling it to dryness ; but this process is not so convenient as pre- 
cipitation. The powder has also been procured by first forming 
in amalgam of the metal with mercury, and then evaporating the 
atter ; but besides being expensive, the fumes of mercury are 
bund to be extremely prejudicial to the health of the operators. 
When gold powder is used, it must be mixed with gum-water 
s a vehicle. Where it is intended to apply leaf gold without 
ny fluxing material to the body of the wares, these should be 
oistened in the requisite parts with a weak solution of gum- 
rabic, which must afterwards be allowed to dry. When the 
old is applied, the porcelain or glass may be made sufficiently 
dhesive by breathing on it. If a flux is employed, it should, 
fter being rubbed very fine with a muller, be diluted with 
eak gum-water, and very thinly spread over the parts which 
\ is designed to ornament ; when very nearly dry, the leaf gold 
laid upon it. 



82 PORCELAIN MANUFACTURE. CHAP. VI, 

Japanners' gold size, moistened to the requisite degree with 
oil of turpentine, is sometimes employed. Waiting then until 
the size is so far dried as to be only clammy to the touch, the 
gold leaf is laid on with cotton wool. As soon as the gold is 
applied, the ware is placed in an oven or muffle, that it may be 
burnt on. 

Some old authors direct the artist to fuse gold with regulus 
of antimony, to pulverize the mass, and to spread the powder 
upon the parts to be gilded, exposing the ware afterwards to 
such a heat as will suffice to evaporate the antimony while the 
gold remains fixed. This method of proceeding is objectiona- 
ble, from the almost impossibility of spreading the powder in a 
sufficiently uniform manner, besides which, part of the gold will 
also be carried off, and some descriptions of glass are even fusi- 
ble with the degree of heat necessary for perfecting the process. 

Circular gold lines are frequently described on small articles, 
such as cups, saucers, and plates. To assist him in tracing 
these with accuracy, the artist employs a portable horizontal 
wheel, the height of which may be adjusted at pleasure, accord- 
ing as the nature of the work requires it to be performed in a 
standing or a sitting posture. The lower part of this wheel i 
somewhat similar to the leg and feet of a claw table, the le 
being bored out for the reception of a stout metallic wire, th 
altitude of which is regulated by means of a thumb-screw. 

The upper or movable part of the wheel has a like tubula 
cavity in its vertical part, by means of which it is dropt on t 
the upright wire, and is. made to rest upon a shoulder fixed o 
the wire, so that the wheel may be made to turn truly upo 
this as its axis : the whole is surmounted by a horizontal table 

In proceeding to use this machine, the artist places his fee 
firmly upon the base of the wheel, and fixing the article to 
ornamented upon the table, he causes the revolution of th 
wheel with his left hand, and holding his brush steadily in th' 
other, describes the circles with the utmost facility and accu 
racy. 

Burnishing, which is the last process performed in the manu 
facture of ornamented porcelain, is usually intrusted to femal 
hands. The implements required for this purpose are, a burn 
isher of agate or blood-stone, some white lead, a piece of shee^ 
skin for wiping the ware, and some vinegar. As extrem 
cleanliness is indispensable, the person engaged in burnishin 
does not even touch either the porcelain or her implements, 
but interposes between them and her hands a piece of clea 
white linen. The agate burnisher should be applied lightl 
on the gilding, following all the ornaments, and never rubbin 
in cross directions, lest the gilding should appear scratched 



CHAP. VI. APPLYING COLORS AND ENGRAVINGS. 83 

After having rubbed the gilding for some time, a little vinegar 
or white lead should be applied to cleanse the surface. This 
being removed with a soft linen rag, the burnishing is recom- 
menced, and continued until the gilding throughout assumes a 
satisfactory appearance. 

It will be remembered, that in the preceding description of 
the colors used in painting porcelain, several were mentioned 
as being unable to support the heat of the gloss-oven. Others, 
however, have not this disadvantage, and will bear the highest 
temperature without injury. Where colors are applied directly 
on the biscuit, no oil is ever ground with them, but they are 
mixed with water only, and the glaze may be added without 
any intervening application of heat. The temperature of the 
enamel-kiln is usually about six degrees of Wedgwood's 
pyrometer, answering to 1857 degrees of Fahrenheit's scale. 

In the year 1817, the Society for the Encouragement of Arts, 
&c., awarded a premium to Mr. R. Wynn, for a list of receipts 
communicated by him, for the preparation of enamel colors and 
fluxes. A copy of Mr. Wynn's paper is inserted in the 35th 
volume of the Transactions of that Society. 
The fluxes are, No. 1. Red lead 8 parts. 

Calcined borax . . 1£ 

Flint powder ... 2 

Flint glass 6 

No. 2. Flint glass .... 10 

White arsenic ... 1 

Nitre 1 

No. 3. Red lead 1 

Flint glass 3 

No. 4. Red lead 9J 

Borax, not calcined 5j 

Flint glass 8 

No. 5. Flint glass 6 

Flux, No. 2 4 

Red lead 8 

The ingredients forming each of these fluxes are melted to- 
gether, and the compounds are then finely pounded for use. 
The recipes for colors are as follows : — 

Yellow. Red lead 8 parts. 

Oxide of antimony .... 1 
White oxide of tin .... 1 
IMix the ingredients well in a biscuit-ware mortar, and having 
put them on a piece of Dutch tile in the muffle, make it grad- 
ually red-hot, and suffer it to cool. Take of this mixture 1 part ; 
of flux, No. 4, 1£. Grind them in water for use. By varying 



84 PORCELAIN MANUFACTURE. CHAP. VI. 

the proportion of red-lead and antimony, different shades of 

color may be obtained. 

Orange. Red lead 12 parts. 

Red sulphate of iron ... 1 

Oxide of antimony .... 4 

Flint powder 3 

after calcining these without melting, fuse one part of the com- 
pound with 2| parts of flux. 
Dark-red. Sulphate of iron, calcined dark . . 1 part. 

Light-red. Red sulphate of iron, . . 1 part. 

Flux, No. 1 3 

White lead 1} 

Brown. Manganese 2^ 

Red lead 8£ 

Flint powder 4 

The style of decoration described in the preceding pages of 
this chapter, is in a great measure confined to the most costly 
descriptions of porcelain. Wares which are fitted by their 
price for being brought into more general use, undergo a differ- 
ent kind of embellishment. A great variety of neatly executed 
patterns are transferred to their surfaces from impressions pre- 
viously printed on paper. Before the introduction of this style 
of ornament, table services of home manufacture were either 
composed of plain Queen's-ware, with occasionally a colored 
edge ; or at best were furnished with a painted border, which 
displayed but little taste in its conception, or ability in its exe- 
cution. This modern improvement has added materially to the 
decent comforts of the middle classes in England, and has more 
than any other circumstance contributed to the great extension 
of our trade in earthenware with the continent of Europe. 
When first invented, and for some time afterwards, the designs 
employed were only imitations of figures and objects seen on 
old blue China porcelain ; but a better taste has since prevailed, 
and artists employed in the composition of patterns no longer 
think it necessary to outrage truth in their representations. 
Landscapes and figures, in conformity with the simplicity of 
nature, and exhibiting a considerable degree of taste, are now 
so common, that this new advantage derived from the printing- 
press is enjoyed without exciting attention or commanding ac- 
knowledgment. 

The method of transferring printed designs to earthern ves- 
sels is thus pursued. The landscape or pattern is engraved 
upon copper, and the color, which is mixed with boiled linseed 
oil, is laid on the plate in the same manner as ink is usually 



CHAP. VI. APPLYING COLORS AND ENGRAVINGS. 85 

applied by copper-plate printers. To increase the fluidity of 
the oil, the plate is then temporarily placed in a stove, a sheet 
of damped tissue paper is laid on it, and both are passed in the 
ordinary manner through the press. The paper, wet with the 
color, is then delivered to a girl, who reduces its size by cut- 
ting away the blank portion surrounding the pattern, and passes 
it to another girl, by whom the impression is applied lightly 
to the ware when in the state of biscuit. A third girl is next 
employed, who, with a piece of woollen cloth rolled tightly in 
the form of a cylinder, rubs the paper closely against the piece, 
in order to press the color sufficiently into its substance. The 
paper thus rubbed is left adhering to the article for an hour, 
when both are placed in a cistern of water, so that the paper 
becomes soft enough to be peeled off without violence, having 
transferred to the biscuit the impression which it had received 
from the copper-plate. 

When the pieces thus printed have stood a sufficiently long 
time to become dry, they are placed in an oven, to which a 
gentle heat is applied, in order, by dissipating the oil, to pre- 
pare the wares for receiving the glaze. This is, of course, 
completely transparent, as otherwise the distinctness of the 
pattern would be impaired. 

For a long time blue, produced from the oxide of cobalt, was 
the only color employed ; but, of late, the potters have extend- 
ed to this pleasing branch of their art all the colors on their 
palette. 

The glaze on printed goods is vitrified in the gloss-oven in 
the manner already described. 

The French potters employ a different method for transfer- 
ring engraved patterns. They cast a sheet of fine glue, about 
a quarter of an inch thick, and diluted while warm to such a 
degree that when cool it shall be perfectly flexible, and have 
the consistence of leather. This glue being applied upon the 
plate, and pressed with the hand, receives the colors according 
to the pattern, which it gives back to the surface of any vessel 
to which it may be applied. Two impressions may generally 
be given in this manner without a fresh application of the glue 
to the plate. After the second has been impressed, the surface 
of the glue is cleaned carefully with water applied by a soft 
brush, and serves again as before. 

The decoration of earthenware by means of engravings is of 
much more recent adoption in France than in England, — not 
having been used in the former country until about the year 
1805. 

In the report made by the Committee appointed to examine 
into the progress of the arts and manufactures in France, as 

H 



86 TORCELAIN MANUFACTURE. CHAP. VII. 

exemplified by specimens exhibited at the Louvre in 1819, and 
to which report allusion has already been made in this Chapter, 
attention is drawn to a curious process, whereby a porcelain 
manufacturer was enabled, on being furnished with an en- 
graved copper-plate, to produce impressions on any scale that 
might be required, whether larger or smaller than the original. 
For this purpose no second plate of copper was needed ; and 
the enlarged or diminished copies might be furnished in the 
course of a very few hours. It is to be regretted that no de- 
scription was given of the means employed for effecting this 
curious process ; but the Committee, who personally witness- 
ed its execution, expressed themselves perfectly satisfied as to 
its efficiency, and awarded an honorary gold medal to the in- 
ventor.* 



CHAP. VII. 

ON THE MANUFACTURE OF TOBACCO PIPES. 

This Manufacture prosecuted to a great extent. — Description of Material. — 
Rolling. — Boring. — Moulding.— Polishing. — Baking. — Description of Kiln 
—Of Crucibles.— Manufacture in Holland.— Originally conveyed there 
from England. 

The manufacture of tobacco pipes forms a branch of the 
potter's art, which has acquired considerable importance from 
the extent to which it is prosecuted ; and it is at the same time 
interesting from the nature of the processes employed. A short 
account of these will, therefore, not be thought misplaced in 
this treatise. 

The clay chiefly employed for the purpose is found in the 
island of Purbeck, in Dorsetshire, and is preferred on account 
of its extreme whiteness. Previously to being used, it must 
be diligently purified from all extraneous matters. The means 
employed for this latter purpose, being the same as have al- 
ready been described, their recital may be omitted here. 

When the purification is accomplished, and the clay has been 
formed into cubical masses, weighing each from eighty to one 
hundred pounds, the workman from time to time cuts off small 
portions, each sufficient to form one pipe, and, first kneading 
them thoroughly upon a table, rolls, them out to nearly the 
form and size of pipes, leaving a bulb at the end for the forma- 
tion of the bowl. In this operation, the skill of the man is 
made apparent by the near approach which this roll makes to 
the dimensions actually required. Persons who have had a 



* Ann. de Chirn. et de Phys. torn. xiii. p. 94. 



CHAP. VII. MANUFACTURE OF TOBACCO PIPES. 87 

competent experience will succeed in this respect to such a 
point as completely to fill the mould, to which the rolls must 
afterwards be transferred, leaving but little surplus clay to clip 
away. 

Fig. 5. 



When the rolls have been formed for a short time, and by 
that means have become sufficiently hardened, the workman 
proceeds to bore the stem by introducing an iron needle. This 
part of the manufacture calls for a great deal of address, and 

Fig. 6. 



can only be satisfactorily accomplished after long practice. In 
performing it, the roll is taken between two fingers, which fol- 
low the point of the needle in its course through the whole 
length of the stem. Near to its point the needle has a circular 
enlargement, the progress of which may be felt through the 
substance of the clay ; and thus the execution of the task is 
somewhat facilitated. The bore must be made as exactly as 
possible in the axis of the stem ; and, in forming it, the needle 
must be pushed forward by means of its wooden handle, with 
a gentle and equable pressure. The part which is to form the 
head or bowl of the pipe is then bent so as to give it the proper 
inclination. 

The mould, into which the stem is next placed, is of copper, 
and divided into two similar parts. On being put to use, the 

Fig. 7. 




whole interior surface of both sections must be slightly touched 
with a brush containing some very limpid oil, that the stem 
may be afterwards delivered from it without difficulty. The 
roll of clay being placed in one section, the other is fitted to it 
according to marks previously made, so as to insure the perfect 
correspondence of the two parts. The mould is then subject- 
ed to the action of a small iron press, in which the two parts 



88 PORCELAIN MANUFACTURE. CHAP. VII. 

are forced together by means of nuts and screws ; and by this 
means its exterior form, with all its ornamei ts, is at once given 
to the pipe. 

The head or bowl has yet to be fashioned. This is in part 
effected by the fore-finger, and more perfectly thereafter by 
means of a stamp or form attached to the mould, and which by 
the action of a lever is introduced within the hollow which the 
finger has made for the purpose. The bore of the stem is then 
continued into the bowl, by pushing the needle up to its handle ; 
any excessive quantity of clay that may have been used is next 
cut away, and the pipe is smoothed by means of an iron or cop- 
per blade. 

The pipes as they are formed are spread out and arranged 
upon a board, that they may be still further dried ; and when 
they have acquired a certain consistence, any roughnesses that 
may appear upon the bowl are rubbed away with an appropri- 
ate horn instrument, which is provided with a groove, of which 
the workman avails himself to perfect the circular form and to 
smooth the edge of the bowl. 

After this the pipes are placed a second time in the moulds, 
that any imperfections which they have acquired in their shape 
may be remedied ; and they are then left until sufficiently hard- 
ened to receive the last polish, which is given by rubbing them 
with flints bored with holes, some of which are of the same di- 
ameter as the stem, while others will admit the head of the 
pipe. If it should then appear necessary, the workman retouch- 
es the different ornaments on the pipe with a kind of bodkin, 
and the needle is withdrawn from the stem. 

These various operations, which bear an appearance of com- 
plexity in the narration, are yet so easy of accomplishment, 
that a clever moulder will furnish 3500 pipes in a week. 

The kiln used for baking the pipes is cylindrical ; having a 
circular fireplace at its bottom. With the exception of the 
spaces required for the circulation of heated air, the interior 
of the kiln is occupied by crucibles, wherein the pipes are 
placed. These crucibles, which are made very thin, are com- 
posed of the same clay as the pipes, and are strengthened by 
the insertion of broken pipe-stems. The bottoms are framed 
of these stems, radiating towards the centre, and having the 
interstices plastered with pipe clay. The top of each is dome- 
shaped ; and a pillar of clay is placed in the centre through the 
whole altitude, which serves at once to strengthen the crucible, 
and to support the stems of the pipes. The side of the cruci- 
ble is provided with six horizontal ledges, proceeding at equal 
distances all round, and upon these the bowls of the pipes are 
arranged, while the stems are made to lean against the central 



CHAP. VII, 



MANUFACTURE OF TOBACCO PIPES, 



89 



pillar. The crucible is capable of containing in these six di- 
visions fifty gross of pipes ; and, if the heat of the furnace is 
properly managed, these will be sufficiently baked in seven or 
eight hours. 

Fig. 8 




The property possessed by tobacco pipes of adhesiveness to 
the tongue, is owing to the great affinity which the clay has 
or water : this quality is much increased by the baking pro- 
cess. 

The manufacture of tobacco pipes is prosecuted to a very 
considerable extent in Holland, whence large quantities have 
ong been exported annually. For the introduction of this art 
the Dutch are indebted to this country ; in proof of which as- 
sertion, Mr. Hollis, who passed through the Netherlands in 
1748, mentions that, having visited very extensive pipe- works 
at Gouda, he was informed by the master of it, that even to 
that day their principal working tools bore English names. 



H2 



90 PORCELAIN MANUFACTURE. CHAP. Vltl. 



CHAP. VIII. 

ON THE PORCELAIN MANUFACTURE OF CHINA. 

Obscurity wherein its Origin is shrouded — Chiefly practised at King-te- 
Ching.— Supposed Superiority of Old China Ware.— Materials employed. 
— Kao-lin — Pe-tun-tse — Their Preparation. — Oils or Varnishes — Their 
Composition.— Hao-che— Its Superiority to Kaolin.— Analysis of Kao- 
lin.— Extent of Factories at King-te-Ching.— Great Number of Workmen 
employed.— Preparation of Materials.— Method of fashioning Utensils.— 
Moulds. — Division of Labor. — Deficiency of Chinese in the Art of Design. 
— Their Excellent Colors. — Numerous Hands employed in Decorating each 
Piece. — Bad Effect of this System. — Blue long the only Color used for 
Painting China Ware.— Mode of Preparing various Colors.— Chinese ig- 
norant of Chemical Science.— Umiam.— Tsou-tchi— Kia-tsing— Method 
of forming it. — Chinese Furnaces.— Passion for Old Porcelain.— Ku-tong. 
— Mock Antiquities. — Reasons for Costliness of China Ware in Europe. 
—High Prices formerly paid in China.— Finest Specimens not brought to 
Europe.— Porcelain Tower at Nan-king. — Chinese Potters prepare Mate- 
rials for the Use of their Descendants. — Common Wares made in China. 
—Attempt of the Emperor to transfer the Manufacture to Pekin.— His 
Want of Success. 

No success has attended any efforts that have been made to 
discover the origin of the art of making porcelain in China, 
and the date of its invention remains veiled in obscurity. The 
most that is known on this head is gathered from the written 
annals of Feou-leang, a city belonging to the same district of 
the empire as King-te-ching, wherein it is recorded that, from 
the time answering to the year 442 of the Christian era, the 
last-mentioned place has enjoyed the honor of supplying the 
imperial court with porcelain, and that one or two mandarins 
have usually been deputed from Pekin to inspect this part of 
the workman's labors. The invention of the art would assured- 
. ly date from a much earlier period than that here mentioned ; 
as it would be long ere the manufacture arrived at such a state 
of perfection as to render it an object of interest to the court. 

It is a very common opinion in China, that the porcelain 
ware made by their ancestors was superior in quality to any 
more recently manufactured. This belief is grounded on the 
fact, that pieces of porcelain are frequently dug from the earth, 
which are uniformly found to be of the very finest description. 
It has been remarked, that this fact is not by any means con- 
clusive evidence upon the subject; the buried pieces were 
most probably concealed, during periods of civil commotion, on 
account of their value, and in order to preserve them for their 
owners, who were without an equal inducement to bury arti- 
cles of more common use. An opinion likewise prevails, and 
is supported by reference to the same fact, that the quality of 
porcelain vessels is improved in beauty by a lengthened burying 



©HAP. Till. CHINESE METHOD OF MANUFACTURE. 91 

in the earth ; and the same answer has been applied to this as 
to the first-mentioned assertion. 

The Chinese employ in the composition of their porcelain 
two kinds of earths, and two oils or varnishes. Of the earths 
one, which is called kao-lin, is found intermixed with particles 
of a shining substance resembling mica ; the other is known 
by the name of pe-tun-tse, and is of a brilliant white, exceed- 
ingly fine in its grain, and soft to the touch. Both these de- 
scriptions of earths are found in mines or quarries situated be- 
tween twenty and thirty leagues from King-te-ching, to which 
place they are brought in small vessels, which are continually 
passing up and down the river of Jao-tcheou for that purpose. 
The hard blocks of pe-tun-tse are cut from the quarry in the 
form and about the size of our bricks, and are brought in this 
state to King-te-ching. The first preparation which these lumps 
undergo, is that of breaking and pounding them coarsely with 
iron mallets, and afterwards more completely in mortars with 
pestles, wrought either by the hand or by a water-wheel. By 
this means the blocks of pe-tun-tse are reduced to an almost 
impalpaple powder, which is thrown into an urn-shaped vessel 
nearly filled with water, and then stirred briskly about, that the 
particles may be intimately mixed with the water. When this 
mixing has been effected, and the fluid has been left during a 
short time to repose, a white creamy substance forms upon the 
surface, to the depth of two or three inches: this, being 
skimmed off, is transferred to another vessel, supplied with 
clear water. The fluid remaining in the first vessel is then 
again stirred up ; another portion forms upon the surface, which 
in its turn is removed, and added to the first skimming ; and 
this process is continued as long as any creamy substance can 
be collected from the surface. What remains in the urn-shaped 
vessel has not been sufficiently ground ; and, being collected 
from the bottom, must be again submitted to the process of 
grinding. 

The skimmings are left to settle in the second vessel, until 
the solid portion has subsided to the bottom, leaving the super- 
natant water perfectly clear : this is then poured off; the sedi- 
ment is transferred to moulds, wherein it remains until nearly 
dry ; and the cakes are then taken out and cut into square 
pieces of the size most convenient for use. The pe-tun-tse is 
then in a fit state for combination with kao-lin ; and the squares 
are sold by the hundred to the porcelain makers. It is not often 
that the manufacturer can venture upon using this material in 
the state wherein he buys it ; the men who have been previ- 
ously employed in preparing the cakes, most generally mix in 
the squares as large a portion of foreign matter as they expect 



92 PORCELAIN MANUFACTURE. CHAP. VIII. 

will escape detection : a separation of these previously to the 
employment of the earth becomes, therefore, needful. 

A similar process is followed in the preparation of kao-lin ; 
but this substance being much less hard than pe-tun-tse, less 
labor is required for its performance* 

The two substances described as oil or varnish are procured, 
one from a combination of pe-tun-tse with another mineral sub- 
stance, and the other from lime. In the preparation of the first 
of these, such stones are preferably selected as have the whitest 
appearance. These undergo the same processes of grinding 
and washing as have already been described ; except that the 
creamy substance, when it has subsided in the second vessel, 
is not all put into moulds, but only the upper and finer stratum 
is gathered for the preparation of this varnish. To each one 
hundred pounds of the substance thus separated one pound of a 
mineral called she-kao, which is a kind of gypsum, is added. 
This stone, which resembles alum in its appearance, is first 
raised in a furnace to a red heat ; and then reduced, by pound- 
ing and rubbing in a mortar, to a very fine powder ; in which 
state its union with the purified pe-tun-tse is effected, the con- 
sistence of the compound being perfectly fluid. 

The preparation of what is called oil of lime, the fourth in- 
gredient required, is thus managed : — Lumps of quicklime are 
first sprinkled with water, and reduced to a powder ; upon this 
a bed of dried fern is placed ; then another layer of lime, cov- 
ered again by fern ; and so on alternately, until the pile having 
reached a moderate height, fire is applied : and when the whole 
of the fern is consumed, the ashes are collected and strewn 
upon fresh beds of fern, which are again fired ; and this burn- 
ing process is repeated five, six, or more times successively, — 
it being held that the more frequently the ashes are burnt, the 
better is the quality of the product. Some ancient Chinese 
annals affirm that, instead of fern, the wood of a kind of medlar 
tree was anciently used ; and that the quality of the porcelain 
was in consequence more beautiful. This wood is now become 
too scarce to be employed for the purpose. The lime and fern 
ashes are next thrown into a vessel containing fair water, and 
she-kao is added in the same proportion as to the creamy dilu- 
tion of pe-tun-tse. This she-kao dissolves ; and the solid matter 
being separated from the water by subsidence, and removed in 
a tolerably fluid state, forms what the Chinese manufacturers 
call the oil of lime, to the agency of which ^iey attribute all 
the lustrous appearance of their porcelain. Lime, when un- 
combined, is infusible, except at a very intense degree of heat ; 
and the fern ashes thus added, are essential, acting as a flux, 
and promoting the fusion of the glaze in the furnace. In mix- 



CHAP. VIII. CHINESE METHOD OF MANUFACTURE. 93 

ing these two varnishes together, only one measure of the oil 
of lime is added to ten measures of that of pe-tun-tse, care be- 
ing taken that the consistence of both is equal. The oil of 
lime is easily, and to the seller profitably, adulterated by the 
addition of water, combined with such a farther portion of she- 
kao as preserves its proper degree of consistency. 

It is said that, since the time when D'Entrecolles communi- 
cated his observations on the porcelain manufacture in China, 
the potters there have discovered a new species of mineral, 
which can be advantageously used in the preparation of porce- 
lain. This is a species of chalky stone, which bears some out- 
ward resemblance to soap, and is declared to possess considera- 
)le medicinal virtues. It is called hao-che ; and when used in- 
stead of kao-lin, the result is porcelain of very fine grain, ex- 
ceedingly light, and much better qualified for receiving colors, 
)ut more brittle, and far dearer in its cost, than the commoner 
kind of ware, the price of hao-che being three times that paid 
for kao-lin. This new substance, when taken from the mine, 
undergoes the operation of a careful washing, to separate from 
t a kind of yellow earth with which it is always found accom- 
)anied : it is then pounded, and treated exactly in a similar 
nanner to that described in the preparation of kao-lin. It is 
iffirmed that hao-che, thus purified, is capable of being made 
nto porcelain without any admixture. 

It is the kao-lin which, although much • softer than the pe- 
;un-tse when taken from the quarry, gives strength and body to 
he porcelain ; and, consequently, this, or some substitute pos- 
sessing the same quality, forms an indispensable ingredient in 
ts composition. It is related that some Europeans, having pri- 
vately obtained some blocks of pe-tun-tse in China, and con- 
veyed them to their own country, vainly endeavored to convert 
hem into porcelain ; which becoming known to some Chinese 
nanufacturers, they deridingly remarked, " that certainly the 
Europeans must be a wonderful people, to go about to make a 
)ody whose flesh was to sustain itself without bones." 

Kao-lin is known, from the particles of mica which it con- 
ains, to have its origin in felspar, or graphic granite. It is in- 
usible with the heat of a porcelain furnace even in China, the 
legree of which must be most tremendous, as some of the ma- 
;erials employed in their glazes could not be vitrified at a lower 
:emperature than would suffice to fuse Cornish granite. The 
Lao-lin quarries of China agree with the mines of Alen^on and 
St. Yrieux near Limoges, where a similar earth is found — all 
)f them having a super-stratum of red, friable, micaceous rock, 
)f the texture of gneiss. The constituent ingredients of kao-lin 
ire found to be — silica 52, alumina 42, oxide of iron 0.33. 



94 PORCELAIN MANUFACTURE. CHAP. VIII. 

The factories employed at King-te-ching for the porcelain 
manufacture are of great extent. They are walled round, and 
contain sheds under which the processes are carried on, as well 
as dwellings for the workmen. The number of people em- 
ployed in one of these factories is very great, as must appear 
when it is considered that almost every piece of porcelain pro- 
duced, however small, passes through more than sixty different 
hands before it reaches a state of perfectness. 

When the purification of the two earths has been completed 
by the processes already described, the next operation is to unite 
them in the requisite proportions. The relative quantities of 
these materials depend upon the quality which it is desired to 
give to the porcelain. — For the finest kind, they mix the kao- 
lin and pe-tun-tse in equal quantities, and diminish the propor- 
tion of the former according as coarser kinds of ware are re- 
quired ; but, for the very coarsest descriptions, the kao-lin never 
forms less than one fourth of the mass. 

The most laborious part of the whole operations of the facto- 
ry, is that of intimately kneading and working the earths to- 
gether, so as to form of the two one homogeneous mass. This 
is performed in pits, which are paved and cemented, wherein 
the workmen continually trample upon the paste, bringing ten 
gether fresh portions by turning it over ; and this work is con- 
tinued without intermission, one set of workmen relieving an- 
other at intervals, as each becomes fatigued by the labor, until 
the mass is thought to be thoroughly mixed, and has been 
brought to a consistence proper for being moulded by the potter. 
The mixture is then removed from the pit; and being divided 
into small portions, is again kneaded with the hands upon large 
slates provided for the purpose. Too much careful industry can 
hardly be exercised in this operation. If the smallest drop of 
water or globule of air be left remaining in any portion of the 
mass, the article which contains that portion will infallibly be 
spoiled by the expansion of the fluid in the oven. The smallest 
grain of sand, or even a single hair, left in the paste, would be 
equally prejudicial, occasioning the porcelain to run, or crack, 
or warp in the baking. 

The pieces are fashioned by the Chinese workmen in a man- 
ner so similar to that adopted in our own potteries, that it would 
be useless to narrate the process. 

The moulds used in the potteries of China for forming pieces 
of multiform shape are made in several portions or divisions, 
which are brought together when used. They are made of a 
yellow unctuous earth, which occurs abundantly in quarries near 
to King-te-ching ; and its preparation by kneading and beating 
is very similar to that bestowed on the porcelain earths. When 



CHAP. VIII. CHINESE METHOD OF MANUFACTURE. 95 

made and used with care, these moulds will last for a long time. 
The Chinese workmen are not content with the work as deliv- 
ered from the moulds, but uniformly finish the article by the 
hand, using a variety of chisels and other tools to toucli up the 
various lines and forms given by the mould, as well as to sup- 
ply its probable deficiencies; so that the potter executes, in 
some sort, the art of a sculptor. In works where different ob- 
jects appear in relievo, these are made separately, and added 
in the way commonly used in our own potteries. 

It may give some idea of the number of hands employed in 
the perfecting of every piece of porcelain to state what D'En- 
trecolles has related to occur with the commonest description 
of tea-cup. The potter has the management of the wheel ; and 
under his hands the cup assumes its form, height, and diame- 
ter. It may be well imagined that this workman does not be- 
stow much labor upon his task, when we are told that for fash- 
ioning twenty-six cups he receives a sum equivalent to about 
three farthings of our money : the cup, accordingly, is delivered 
by him in a very imperfect state to a second workman, who fits 
it to its base. From him it passes immediately to a third man, 
who, by means of a mould, placed on a kind of lathe, corrects 
the imperfections of its shape. A fourth man, by the aid of a 
chisel, corrects the inequalities and unevennesses of the edges, 
and pares the cup to a substance which renders it sufficiently 
transparent. In the course of this operation he has frequently 
recourse to water, in order by moistening to prevent the crack- 
ing or breaking of the cup. A fifth workman then smooths the 
inside by turning it gently on a mould. Considerable care is 
required in this stage to prevent any warping or the formation 
of any cavity in the cup. Other men then, according to the 
description of cup which it is intended to produce, add either 
the handle, or some ornaments in relievo, or make sunken im- 
pressions. The operation that immediately precedes the first 
baking of the cup, is that of rounding and hollowing the inside 
of its foot : this is performed with a chisel. 

By this division of labor, the work is found to proceed with 
greater regularity and rapidity. Incessant attention to one op- 
eration, and that of a very simple kind, gives to each workman 
considerable dexterity and facility in its performance ; and no 
time is lost in the changing of implements, as must be the case 
if one man had to conduct the manufacture through its several 
stages. 

Very large pieces of porcelain are made at King-te-ching. 
These are sometimes of such magnitude, that they must first 
be formed in two, three, or more sections ; each one of which 
requires to be supported during its formation by three, or more 



96 PORCELAIN MANUFACTURE. CHAI\ VIII. 

men. When the different portions are sufficiently dry, they 
are united together with slip, in the same manner as handles 
are attached ; and the seams are smoothed and polished with an 
iron instrument, so that, upon their being afterwards covered 
with varnish, it is not possible to discern the points of junction. 

The celebrated traveller Marco Polo mentions the vast ex- 
tent to which the manufacture was carried at the time of his 
residence in the Celestial Empire, and states that eight porce- 
lain cups might then be purchased at the low price of a Vene- 
tian groat.* 

Among the Chinese, the art of design has never advanced 
beyond the very first steps. These people appear ignorant of the 
commonest rules of perspective ; and their drawing, especially 
where attempts are made to describe the human figure, is 
wretched in the extreme. To make some amends for this, the 
colors which they employ are exceedingly lively and brilliant, 
so that European artists have found it a difficult task to vie with 
them in this respect. In examining the painted porcelain of 
this singular people, one is almost led to imagine that their 
artists have been debarred the sight of the objects which they 
attempt to represent, as otherwise some among them must 
surely have possessed sufficient innate taste to have led him 
from the general track, and instead of the miserable caricatures 
that disgrace their labors, to have made some approach towards 
the truth in his delineation of natural objects. 

The system of distributing the work among a great number 
of hands, which is found so successful in the formation of porce- 
lain, is also pursued in the painting department. One artist 
forms only colored circles about the edges; another traces 
flowers, which a third paints ; a fourth delineates nothing but 
mountains ; a fifth describes water ; a sixth traces the outline of 
birds, which a seventh fills up with colors. Other artists trace 
and color animals ; others again perform the same tasks with 
the human figure, and in this way every object of art and na- 
ture found upon their porcelain is the work of a particular 
artist, who does not attempt the delineation of any other sub- 
ject. To this system, so useful in conducting every merely me- 
chanical operation, may possibly be owing the continued ad- 
herence to old and faulty methods. The celerity which it is 
calculated to produce is unfriendly to the improvements sug- 
gested by genius; and if even one artist among the crowd 
should be found with taste enough to aim at forming and em- 
bodying juster conceptions, his approaches to nature would only 

* Marsden's translation, 4to edition, page 560. 



CHAP. VIII. CHINESE METHOD OF MANUFACTURE. 97 

serve to render more glaring the deformities produced by his 
fellow-laborers, and would, therefore, be wholly inadmissible. 

It is said, that for many ages the Chinese used only white 
porcelain. Tradition adds, that its whiteness was most bril- 
liant, that the pieces were altogether faultless, and that the 
only name by which they were known when exported to other 
kingdoms was that of " the precious jewels of jao tcheou." 
Blue was the first color wherewith they ornamented pottery, 
but the employment of all other colors very speedily followed 
upon the introduction of this one. At first, and for a long 
time, their blue color was prepared from a very fine kind of 
lapis lazuli, which is native with them ; but they now import 
smalt from England, at a price so much below that which their 
own pigment had cost, that they have abandoned its manufac- 
ture, and depend upon their foreign supply. The fine deep-blue 
sometimes found upon specimens of old Chinese porcelain is 
much admired and valued by virtuosi, and it is regretted that 
this color is not used at present. It has been conjectured that 
the Chinese, who unquestionably possess cobalt, most probably 
employed its oxide also in the production of this esteemed blue 
color before they were enabled by their commerce with Euro- 
peans to substitute for it our cheaper pigment; that their 
method of preparing the ore of cobalt was such, that it retained 
the arsenic with which it is always found in combination, and 
that, consequently, its color proved much deeper and richer 
than the preparation made by us from the same mineral. Our 
process being performed in a reverberatory furnace, the arsenic 
is driven off in fumes. There are some kinds of cobalt which 
are made to yield smalt without this previous roasting, and the 
superior color which in such case is always produced is attribu- 
ted to the presence of arsenic ; since if this mineral be added to 
smalt while in a state of fusion, the color will be rendered much 
deeper. The preparation of smalt from cobalt without the aid 
of fire is more expensive and the produce less in quantity than 
where the common process is followed. The French manufac- 
turers procure their smalt by dissolving cobalt in nitric acid 
(the aqua fortis of commerce), and then precipitating ; and it 
might be well for our porcelain makers to try the effect of this 
method. 

The red color used by the Chinese is made from common 
green vitriol or copperas (proto-sulphate of iron), which goes 
with them by the name of tsa-fan. This materia] they calcine 
in a crucible, continuing to apply fire for so long a time as 
thick black fumes are seen to escape from a hole made in the 
top of the crucible ; but when these fumes are succeeded by a 

1 



98 PORCELAIN MANUFACTURE. CHAP. VIII. 

light and thin cloud, they judge that the process has been car- 
ried sufficiently far, and remove the crucible from the furnace, 
previously, however, withdrawing a small quantity of the color 
for inspection, as the test here mentioned is not unerring. 
When the color proves good, the crucible is left to cool gradu- 
ally, a cake of red matter is then found at the bottom, and a fur- 
ther quantity, in the form of fine powder adhering to its sides. 
This latter, being the purest and finest color, is kept separate 
from the cake. Copperas affords about one fourth of its weight 
of this color, which alone is used for producing all the various 
shades of red in the porcelain works of King-te-ching. 

White porcelain, made in China, owes much of the fine bril- 
liancy of its color to the oils or varnishes before described ; but 
when a brighter and finer hue than can be thus produced is 
needed, a mixture of the following kind is prepared. The 
shores of some of their rivers furnish a species of agate, which 
is without veins and nearly transparent, so that it approaches 
to the nature of crystal. This stone is calcined to a white pow- 
der, and then ground as fine as possible. To every ounce of 
this they add two ounces of white lead (ceruse,) also in fine 
powder, and these being mixed with the varnish, the whole is 
laid on the porcelain in the same way as other colors. Accord- 
ing to the descriptions given to us, this compound, besides be- 
ing used for the production of a brilliant white, forms also the 
ground or basis of several other beautiful colors. Their green, 
which is prepared from the oxide of copper, is said to be con- 
verted into a fine violet color by admixture with the white just 
described. Such a change as this must of course be the effect 
of chemical action promoted by the heat of the furnace. The 
mere mechanical mixture of white with green would only re- 
duce the depth of its shade. A very small proportion of the 
white suffices, it is said, to produce a very deep violet, and the 
hue is rendered lighter in proportion as the quantity of white is 
increased. Their yellow is said to result from the mixture, in 
due proportions, of this white with copperas (proto-sulphate of 
iron). The accounts we have of those processes among the 
Chinese, which depend upon chemical laws, are given with so 
little regard to accuracy, and betray so great a want of scien- 
tific acquirement, that these descriptions of their mode of pre- 
paring colors cannot be received with any satisfaction. 

The Chinese painters of porcelain usually mix their colors 
with gum water, in which a small portion of either saltpetre 
(nitrate of potass), white lead, or copperas has been first dis- 
solved. Where a red color is used, the porcelain oil or varnish 
is applied with it. This color is laid on the ware when in the 
state of biscuit, that is, when it has been once in the oven, but 



CHAP. VIII. CHINESE METHOD OF MANUFACTURE. 99 

it requires the heat of the second baking to bring out all its re- 
quisite shades and tints. 

Black porcelain, ornamented with gold, known under the 
name of umiam, is much esteemed in the East. The black is 
produced by mixing three drachms of deep blue, with seven 
drachms of the varnish, which they call oil of stones. The black 
thus prepared is laid on when the porcelain is first dried, and 
when the black is also thoroughly dry, the vessel is baked. 
The gold is then laid on, and the piece is subjected to another 
baking in a furnace peculiarly constructed for the purpose. 
The gold is ground in water to a very fine powder ; and when 
this has been very gradually dried in the shade, one tenth of its 
weight of white lead is added, the mixture is incorporated 
with gum water, and laid on in the same manner as colors are 
applied. 

The Chinese have a kind of porcelain, which is in much re- 
pute with them, called tsou-tchi. This has the appearance of 
having been broken, and of having its fractured edges brought 
together and cemented, and then covered with the varnish ori- 
ginally used. This effect is produced through the peculiar na- 
ture of the varnish employed, which never spreads evenly, but 
has a tendency when in fusion to rim into veins and ridges of 
various and uncertain forms. This varnish is made from a sort 
of agate stones, reduced by calcination to a white powder, 
which after being long ground in a mortar is carefully washed, 
and used when of the consistence of cream. It has been sug- 
gested that crystal would probably answer this purpose as well 
as the coarse agates of the Chinese ; and among all the de- 
mands of fashion which is ever seeking for something new, it 
might perhaps serve the interest of some manufacturer to put 
this suggestion to the proof. 

Another kind of porcelain, much esteemed by the Chinese, 
is called by them kia-tsing, which signifies pressed azure. In 
vessels of this description the colors appear only when the 
cups are filled with liquid. The manner of making porcelain 
so as to produce this effect is as follows : — The cup is made 
very thin, and after having been once baked, the colors are ap- 
plied in the required forms on its inner surface. When dry, a 
coating of porcelain earth, the same as that already composing 
the cup, must be laid on the inside ; over this, the usual varnish 
is laid, so that the colored figures are inclosed between two 
coats or bodies of the ware. The outside, already very thin, is 
then ground down almost to the painted figures, which are 
thus made to appear externally, when they must be covered 
anew with a coat of varnish so as to be scarcely perceptible 
from the outside, until the vessel being filled with liquid, this 



100 PORCELAIN MANUFACTURE. CHAP. VIII. 

acts as a kind of foil behind, and throws out the figures which 
before were obscured. So much carefulness is called for in 
the production of kia-tsing, that the art is very seldom prac- 
tised. 

Another admired art among this people is that of producing 
the semblance of various figures upon pure white porcelain, 
whose surfaces are yet entirely smooth. Having fashioned a 
vessel, with the finest materials and extremely thin, it must be 
polished inside and out, when a stamp cut with the requisite 
figures in relief must be pressed upon the inner surface of the 
unbaked vessel. The finest white varnish must next be applied 
over its entire surfaces, so that the cavities impressed by the 
stamp are filled by it, and the smoothness of the inner surface 
is restored. When the ware is baked, the varying thicknesses 
of the more opaque varnish will be apparent through the trans- 
parent sides of the cup, and the whole of the figures will then 
be seen as finely and accurately traced as if painted on the out- 
side. 

The methods employed by the manufacturers of King-te- 
ching in applying the varnish, vary with the different qualities 
of the wares under operation. For very fine and thin porce- 
lain two exceedingly thin coatings are very carefully applied, 
and some dexterity is required, both with regard to the quantity 
laid on, and the equable manner of its application. To pieces 
of inferior quality, as much varnish is applied in one coating 
as is comprised in the two layers just mentioned. The foot of 
the vessel is never properly formed until this stage of the 
manufacture, and after the painting and varnishing have been 
completed, when this part is finished on the wheel, and var- 
nished likewise. The work is then fit to be placed in the oven. 

The construction of furnaces and the system followed in 
baking porcelain in China differ so little from the structure and 
method pursued in England, that little need be said here con- 
cerning them. It has already been mentioned that the nature 
of the materials employed calls for a much higher degree of 
heat than is necessary in our potteries. To insure this, the 
Chinese are very careful in providing a rapid draught, and in 
the incessant feeding of their furnaces with small billets of 
wood, so as to insure its most rapid combustion. The learned 
Jesuit D'Entrecolles observes, as a thing quite unaccountable, 
and even inconceivable, if he had not witnessed the fact, that 
notwithstanding the enormous consumption of wood during so 
many hours, none of its ashes are ever found upon the hearth 
of the oven. There would have been greater reason for aston- 
ishment had the contrary fact appeared. The rapid draught 
excited by the disposition of the oven, and the excessive degree 



CHAP. VIII. CHINESE METHOD OF MANUFACTURE. 101 

of its temperature, would serve to carry away completely 
through the flue so light a substance as wood ashes. 

The taste for old porcelain appears to prevail fully as much 
in China as it has ever done in this country. It is asserted by 
some persons, that such as was made in former days was not 
only composed of finer materials, but was more perfect in the 
mode of its manufacture. Unfortunately for this assertion, 
there are workmen at King-te-ching, who make it their occu- 
pation to counterfeit these much-coveted relics of antiquity, 
which are called ku-tong, and in this they succeed so as to de- 
ceive the most observant connoisseurs. In the preparation of 
these mock antiques there is but little variation from the meth- 
ods usually practised. They are made thicker than modern 
porcelain, and are made to undergo the ceremony of burial for 
one or two months in the most lothesome sink of filth which 
can be found, by which means every appearance of newness is 
effaced. 

Several reasons are assigned for the high price at which 
Chinese porcelain is sold in Europe. One of these is, that owing 
to their very unscientific manner of conducting the baking 
process, it rarely happens that some, and sometimes a very con- 
siderable portion, is not spoilt by unequal or excessive heat, and 
converted to a deformed and shapeless mass. Another reason 
for dearness is, the constantly diminishing supply of the mate- 
rials used, and more especially of fuel, which becomes very ex- 
pensive. It is added, that as those pieces which are prepared 
for the markets of Europe, are of patterns unacceptable to the 
taste of home consumers, and as the factors are exceedingly 
particular in rejecting every article which exhibits the slightest 
defect either in form or color, the prices paid to the manufac- 
turers for such as are accepted must be sufficiently high to in- 
clude the cost of those which are rejected. Notwithstanding 
these circumstances, the prices at which porcelain is now fur- 
nished in China are materially less than those demanded in an- 
cient times, when, we are informed, as much as 100 crowns 
were given for a single urn at the seat of manufacture. The 
emperor monopolizes the finest specimens of porcelain manu- 
factured in his dominions, and it has thence been asserted, that 
none which has ever found its way to Europe gives an adequate 
idea of the perfection to which the Chinese have attained in 
this manufacture. The Porcelain Tower erected at Nan-king 
offers proof sufficient of the very durable nature of their manu- 
facture. This building is of an octagonal shape, is of nine sto- 
ries, and very nearly 300 feet high, and its entire surface is co- 
vered with porcelain of the finest quality. Although this sin- 
gular and beautiful edifice has been erected more than 400 

12 



102 PORCELAIN MANUFACTURE. CHAP. VIII. 

years, it has hitherto withstood all the alternations of seasons, 
and every variety of weather, without exhibiting the smallest 
symptom of deterioration. 

The intimate mixture of the two earthy materials so essen- 
tial to the production of good porcelain is much more perfectly 
attained, if, after the employment of the mechanical means al- 
ready described, the united mass be left for a considerable time 
before its employment. The Chinese frequently extend this 
interval to a space of fifteen or twenty years ; and instances are 
not uncommon, where the provident care of a parent leads him 
to prepare as much porcelain clay as will- suffice for his son's 
use, during the whole period of his life. 

The Chinese excel in the manufacture of brown earthen- 
ware, which being sold at a very low price, is used commonly 
throughout the empire. Porous vessels for cooling water are 
also made by them of fuller's earth, which is principally com- 
posed of alumine and very pure silex, in combination with oxide 
of iron. The name by which porcelain is distinguished in this, 
the country of its earliest production, is tse-ki. 

An attempt was once made by the government to remove the 
seat of manufacture to the imperial city of Pekin. This, how- 
ever, although no effort was spared in the business, proved un- 
successful, and the sole prosecution of the art reverted to King- 
te-ching, where, according to the statement of different travel- 
lers, there are established 500 factories, giving employment to 
more than a million of artisans. There appears no good reason 
for believing that the manufacture would not have been prose- 
cuted with equal success at Pekin, if those who directed it had 
been so disposed ; and the different result which has been re- 
corded is supposed to have arisen from the disinclination of the 
manufacturers to be brought so closely within the control of a 
government supereminently famed for meddling with the pri- 
vate concerns of its subjects. 



MANUFACTURE 

OP 

GLASS. 



A 

TREATISE 

ON THE 

PROGRESSIVE IMPROVEMENT AND PRESENT STATE 

OF THE 

MANUFACTURE OF GLASS. 



CHAPTER I. 

ON THE NATURE AND PROPERTIES OF GLASS, AND THE HIS- 
TORY OF ITS MANUFACTURE. 

Nature of Glass.— Its various Properties.— Its Utility.— The Assistance it 
lends to Science.— Excessive Prices formerly paid.— Origin of its English 
Name.— Aristotle's Problems.— First Invention ascribed to the Phoeni- 
cians.— Manufactories of Alexandria.— Utensils found in Herculaneum. 
—Malleable Glass.— Tax on Glass by Alexander Severus.— Portland Vase. 
— Glass employed in forming Windows.— Privileges granted to Manufac- 
turers in France.— Plate-Glass Casting.— Establishment at St.Gobain.— Its 
early Failure, and Revival.— Manufacture commenced in England.— Of 
Flint Glass.— Of Plate Glass.— Chinese unacquainted with Glass-making. 
— Importance of the Manufacture in England.— Glass made a Source of 
Revenue. 

Many circumstances contribute to render glass one of the 
nost curious and interesting of manufactured substances. 

Although perfectly transparent itself, not one of the mate- 
rials of which it is made partakes of that quality. Exceedingly 
)rittle while cold, it becomes, by the application of heat, so re- 
markably flexible and tenacious as to be convertible into every 
form that fancy may dictate or convenience suggest. Its great 
luctility is shown in a very striking manner by the slender 
ilaments — small as the fibres of spider's web — into which it is 
pun for ornamental purposes. Many hundred feet of these 
ilaments may be drawn out from a heated mass in the space 
)f one minute. Its pliancy and elasticity are proved by the 
acility with which, when in the state just mentioned, it may 
)e bent and retained in various forms, and by the energy 
wherewith its original shape is resumed at the moment of re- 
ease from its constrained position. 

The impermeability of glass to water, even under a consid- 
erable degree of pressure, is well ascertained. A few years 
go, the reverend Mr. Campbell, while on a voyage to South- 
ern Africa, among other philosophical experiments wherewith 
le amused himself, caused two globular glass bottles hermet- 
cally sealed to be lowered by means of leaden weights to the 
lepth of 1200 feet beneath the surface of the sea. These, 



106 MANUFACTURE OF GLASS. CHAP, I. 

through the united and continuous exertions of ten men during 
fifteen minutes, were again drav^n up, and were found to be 
perfectly empty. 

The continued exposure of glass to the greatest heat where- 
by it is melted, does not produce any sensible diminution in its 
weight and quantity, or any alteration of its properties. It is 
capable of receiving colors, and of retaining them in all theii 
lustre for an indefinite period. The strongest acids — with one 
exception that will be noticed — have no effect upon it ; a cir 
cumstance that renders glass additionally useful in assisting 
the researches of chemists. It is capable of receiving the 
most perfect polish, preserves all its beauty, and does not lose 
the smallest portion of its substance by the longest and most 
frequent use. 

The admirable qualities and important uses of glass hav 
been so happily pointed out by one of the most celebrate 
writers of the last century, that no apology will be needed for 
the insertion of the passage. 

" Who, when he saw the first sand or ashes by a casual in 
tenseness of heat melted into a metalline form, rugged with 
excrescences, and clouded with impurities, would have im- 
agined that in this shapeless lump lay concealed so many con- 
veniences of life as would in time constitute a great part of the 
happiness of the world 1 Yet by some such fortuitous liquefac 
tion was mankind taught to procure a body at once in a high 
degree solid and transparent, which might admit the light of 
the sun, and exclude the violence of the wind ; which might 
extend the sight of the philosopher to new ranges of existence, 
and charm him at one time with the unbounded extent of the 
material creation, and at another with the endless subordina- 
tion of animal life ; and what is yet of more importance, might 
supply the decays of nature, and succor old age with subsidiary 
sight. Thus was the first artificer in glass employed, though 
without his own knowledge or expectation. He was facilitat- 
ing and prolonging the enjoyment of light, enlarging the ave- 
nues of science, and conferring the highest and most lasting 
pleasures ; he was enabling the student to contemplate nature, 
and the beauty to behold herself." * 

The utility of a substance which is daily and hourly rendered 
serviceable by all classes of persons in almost every human 
habitation cannot need to be exemplified. The aids which it 
offers to scientific researches are almost equally apparent. To 
notice the particular arrangements whereby the chemist, the 
naturalist, or the astronomer avails himself of some of the va- 

* Rambler, No. ix. 



CHAP. I. HISTORICAL NOTICES. . 107 

rious properties of glass in pursuing his investigations, would 
lead to descriptions which, although interesting in a high de- 
gree, are foreign to the object of this treatise, wherein little 
more than incidental notices can be given, on points that have 
relation to improvements in the manufacture. 

It may be useful, however, to notice here an error, not un- 
frequently made, from observing glass to be the only transpa- 
rent material used in making spectacles, opera glasses, and 
other optical instruments. Persons are induced, from this cir- 
cumstance, to ascribe to the peculiar quality of glass the ex- 
clusive power of modifying the apparent magnitude, brightness, 
and distinctness, of objects seen through it. This, however, is 
not an exclusive property of glass, but belongs to every trans- 
parent substance having a density different from that of the air 
which surrounds the observer. It depends also, not alone on 
ithe inherent qualities and density of the transparent substance 
[through which the objects are viewed, but also on the form of 
e surfaces which bound that substance, and on various other 
[circumstances not necessary to be noticed more particularly 
here. The reader will, therefore, recollect, that the optical 
properties of glass are common to the diamond and other trans- 
parent solids, to all transparent liquids, and even to gases. 
|Grlass is commonly used on account of its cheapness and dura- 
bility, and for other reasons of convenience. 

It is impossible, however, wholly to dismiss this subject un- 
accompanied by expressions of admiration at the genius of those 
naster spirits, who, by their discoveries and inventions, have 
Rendered glass subservient to purposes that open and enlarge 
he field of human knowledge in some of those branches of nat- 
iral philosophy which tend most to refine the nature and exalt 
he character of man. 

Familiarized as we are to the use and appearance of glass, 
et no person can ever become indifferent to its advantages, or 
usensible to its beauty. Neither can we feel astonishment at 
he admiration which induced the ancients, while the art of 
paking it was little practised, and in those countries where it 
/as not yet established, so greatly to covet the possession of 
lass vessels as to purchase them at prices which to us appear 
xorbitant. We are told that the emperor Nero gave for two 
ups with handles 6000 sestertia, a sum nearly equal to 
0,000/. of our money. These vessels were not of any extra- 
-dinary size, but were thus highly valued on account of their 
erfect transparence, and resemblance to crystal. 
The name whereby this material is known to us is generally 
id to be derived from the Latin, and to have been suggested 
f its great similarity in appearance to ice {glades.) It has 



108 MANUFACTURE OP GLASS. CHAP. I. 

been remarked, however, that the common Latin designation 
is vitrum ; and as the Romans gave this name also to the plant 
which we call woad, and which our remote ancestors called 
glastum, it is imagined that glass obtained the same distinctive 
appellation, because of the bluish tint which it usually exhib- 
ited. There is as little probable foundation for one as for the 
other conjecture, nor is the question of much importance, since, 
whichever way it might be determined, no light would be 
thereby thrown upon any point of interest concerning the origin 
of the manufacture, which, although involved in the most im- 
penetrable mystery, is yet known to have existed long before 
its introduction among the Romans. 

The passage in the book of Job (ch. xxxvii. v. 18.) wherein 
mention is supposed to be made of glass, has been adduced by 
Neri in proof of its remote origin. Unfortunately for the cor- 
rectness of this opinion it has been found, that in many ancient 
versions, instead of the glass of the Vulgate and Septuagint, 
other substances which have diaphanous and shining properties 
are mentioned. In fact, the word in the original Hebrew has 
been frequently used, according to the fancy of translators, to 
signify different bodies possessing lustre and transparency. 

The two problems of Aristotle — if, indeed, they were pro- 
pounded by that philosopher — "Why do we see through 
glass]" and "Why is it not malleable]" comprise, perhaps, 
the earliest written mention made of the substance. Theo- 
phrastus, whose writings are not half a century later than the 
time of Aristotle, mentions the use of sand from the river Belus 
in making glass ; and from that date (300 years b. c.) a know- 
ledge of the material was pretty generally diffused. If reli- 
ance is to be placed upon the statement, that the celebrated 
sphere of Archimedes was made of glass, the art must in his 
time (209 years b. c.) have arrived at a- considerable degree of 
perfection. 

Many authorities concur in assigning the merit of the inven- 
tion to the Phoenicians ; and the assertion of Pliny is often re- 
peated, which attributes the discovery to accident. Some 
storm-driven mariners were boiling their food on the sands at 
the mouth of the river Belus — a small stream running from the 
foot of Mount Carmel in Galilee — where the herb kali was 
growing abundantly, and are said to have perceived that the 
sand, when incorporated with the ashes of this plant, melted 
•and ran into a vitreous substance. It is certain that the sand 
about this spot was well adapted to the manufacture of glass, 
and probably the glass-houses of Tyre and Sidon were supplied 
thence with this material, which may have given rise to the 
tradition. 



CHAP. I. HISTORICAL NOTICES. 109 

That the ancient Egyptians were well acquainted with the 
method of making glass cannot be doubted. The beads where- 
with some mummies are adorned, although composed of earth- 
enware, have an external covering of glaze, which is true 
glass covered with a metallic oxide; and recent searchers 
have discovered among the tombs at Thebes some pieces of 
glass of a blue color, similar in their composition to the glazing 
on the beads just mentioned. 

The glass-houses of Alexandria were long famed -for the 
skill and ingenuity displayed by their workmen. The Romans 
were, at one time, supplied with a great part of their glass 
ware from that city. A coarse and impure manufacture of 
drinking vessels had been prosecuted at Rome from the time 
of Nero; but the art could have made only a slow progress 
notwithstanding the encouragement offered by the high prices 
at which glass wares of foreign make were sold in the impe- 
rial city. The emperor Hadrian, while at Alexandria, re- 
ceived from a priest some glass cups of various colors, which 
had been used in the worship of the temple, and transmitted 
them to Rome as objects of great value and curiosity, with an 
injunction that they should be used on festivals and other great 
occasions. 

Utensils of glass have been found among the ruins of Hercu- 
aneum, which city was destroyed in the reign of the empe- 
or Titus, by the same eruption of Mount Vesuvius which cost 
the elder Pliny his life. It does not appear that glass was used 
or admitting light to dwellings in Herculaneum, the largest 
louses having windows made with a species of transparent talc. 
In the British Museum are four large cinerary urns made of 
^reen glass, which have been pronounced by a very competent 
mthority favorable specimens of the proficiency of the ancients 
n the art of glass-blowing. These are found vases of an ele- 
ant form, furnished with covers and two double handles. The 
brmation of these handles is, it is said, "such as must convince 
my person capable of appreciating the difficulties which even 
he modern glass-maker would have to surmount in their exe- 
cution, that the ancients were well acquainted with certain 
3ranches of the manufacture." * 

Several ancient authors (Dion Cassius, Petronius Arbiter, 
md Isodorus) relate, that in the reign of Tiberius, an archi- 
ct, who had been banished from Rome on account of his great 
popularity, having, in his retirement, discovered the means of 
so far altering the nature of glass as to render it malleable, 
ventured to return to Rome, in the hope of securing both a re- 

* Memoir on Glass Incrustations, by A. Pellatt, Esq. 

K 



110 MANUFACTURE OF GLASS. CHAP. I. 

mission of his sentence and a reward for his invention. This 
discovery not agreeing, however, with the supposed interests 
of the tyrant, w T ho feared lest the value of gold might be low- 
ered by its means, the architect was beheaded, and his secret 
died with him. This is, probably, only another version of the 
story related by Pliny, of the same important discovery having 
been made by an artist in Rome, when such of the populace as 
imagined that their interests would be injuriously affected 
thereby conspired together and destroyed his dwelling. 

A similar discovery, attended by results as unsatisfactory, and 
which is said to have occurred in France in the more modern 
times of Louis XIII, is recorded by Blancourt. He says, that 
the inventor having presented a bust formed of malleable glass 
to the cardinal Richelieu, was rewarded for his ingenuity by 
perpetual imprisonment, lest the " vested interests" of French 
glass manufacturers might be injured by the discovery. 

Without venturing altogether to deny the truth of these sto- 
ries, it would be hard to subject to the charge of presumption 
those persons who entertain doubts upon the matter. It does 
not, certainly, prove the incorrectness of the statements, that 
no subsequent examiner into the arcana of nature has been 
equally fortunate ; and it is assuredly possible that some suc- 
cessful investigator may yet be the means of revealing that 
which has already been thus ascribed to more than one experi- 
menter. 

Improbable as the achievement of this would seem, it would 
be scarcely more extraordinary than the transformation of linen 
rags into sugar, or the conversion of saw-dust into " wholesome, 
palatable, and nutritious food." The purposes both of use and 
of ornament to which glass would in such a case be applied 
are almost endless, and their importance can hardly be over- 
rated ; nor should we" in these days have occasion to fear, lest 
the insensate obstructions of some modern Tiberius or Riche- 
lieu should step between the discoverer and the promulgation 
of his secret. 

According to our present amount of knowledge, the chance 
of realizing such a discovery is, however, limited within the 
barest possibility. The quality of malleability is in direct con- 
tradiction to that of vitrification; the existence of the one state 
seems to be incompatible with that of the other. Some me- 
tallic substances when greatly urged by fire are made to ap- 
proach towards the state of glass, and then lose their mallea- 
bility ; a fact which almost implies the impossibility of impart- 
ing the latter property to glass. Kunkel has indeed observed, 
that it is possible to produce a composition having an external 
glassy appearance, which should be pliant and capable of being 



CHAP. I. HISTORICAL NOTICES. Ill 

wrought under the hammer ; and Neumann tells us, that in the 
fusion of muriate of silver a ductile kind of glass is formed, 
which may be moulded or turned into different figures, and 
which may be pronounced in some measure malleable ; facts 
to which Henckel has referred in order to account for the tra- 
ditionary stories of the ancients. 

The Latin writers of the Augustan age make frequent men- 
tion of glass. Virgil compares to it the clearness of the water 
in the Fucine Lake (^En. vii. 759.) ; and Horace speaks of the 
lustre and transparency of glass in a way which shows that it 
could then be made with a considerable degree of perfection. 
In the year 220 a tax was laid by Alexander Severus upon the 
glass manufacturers of Rome, who at this time existed in such 
numbers, that a principal quarter was assigned to them in that 
city, wherein they might carry on their processes. This tax 
was still levied in the reign of Aurelian. 

The most celebrated specimen of antique glass is the vase, 
which during more than two centuries ornamented the Barber- 
ina palace, and which, having been subsequently purchased by 
the late duchess of Portland, is better known in this country 
as the Portland vase. This much-admired production was found 
about the middle of the sixteenth century, inclosed in a mar- 
ble sarcophagus, and deposited in the tomb of Alexander Seve- 
rus, who died in the year 235. The body of this vase, which 
for a long time was erroneously supposed to be formed of por- 
celain, is made of deep blue glass, and is ornamented with 
white opaque figures in bas-relief, which are designed and 
sculptured in the style of cameos with a degree of skill which 
is truly admirable. 

Glass melted and cast into plates, is said by St. Jerome to 
have been used in his time (a. d. 422,) to form windows. About 
ei century later, Paulus Silentiarius mentions the windows of 
the church of St. Sophia at Constantinople which were covered 
with glass ; and from this period frequent allusions to the simi- 
lar use of glass are met with in various authors. 

Long before the establishment of the manufacture within 
this island, glass was known and used in England. The Vene- 
tians who traded with this country in very remote times fur- 
nished this among other articles of commerce in exchange for 
tin. The erudite Pennant is of opinion, that glass-making in 
Britain dates prior to the Roman invasion. The Druids were 
Accustomed to impose upon their more ignorant followers by 
means of clumsily-formed beads of colored glass, which they 
pretended were endued with the quality of guarding their pos- 
sessors from evil. 

The venerable Bede, who lived very near the time, and who 



112 MANUFACTURE OF GLASS. CHAP. I- 

therefore had good opportunities for ascertaining the fact, has 
asserted in his history of Weremouth, that in the year 674 the 
abbot Benedict sent for artists from beyond seas to glaze the 
windows of the church and monastery of Weremouth in Dur- 
ham, and that these men were our first instructors in the art 
of making window-glass. This art, however, took root but 
slowly among us ; and it was not until the eleventh century 
that glass windows were at all commonly used, either in pri- 
vate dwellings or in public and religious edifices. Previously 
to this time, light was imperfectly transmitted through linen 
cloths or wooden lattices. The houses of the commoner people 
were not, indeed, furnished with this luxury until the thirteenth 
and fourteenth centuries, in which respect our ancestors were 
greatly behind the inhabitants of Italy and France. 

The following curious entry, extracted from the Northum- 
berland household book, makes it apparent that at a much later 
period than the one just mentioned, the comfort of glazed win- 
dows was not considered as a matter of course even in estab- 
lishments where great state and magnificence were maintained. 
This entry occurs in the minutes of a survey of Alnwick Cas- 
tle made in the year 1567 : — 

"And because throwe extream windes the glasses of the 
windowes of this and other my lords castels and houses here in 
the country dooth decay and waste, yt were good the whole 
leightes of everie windowe at the departure of his lordshippe 
from lyinge at anie of his sade castels and houses, and dowring 
the time of his lordshippes absence or others lyinge in them 
were taken doune and lade up in safetie ; and at sooch tyme as 
ether his lordshippe or anie other sholde lye at anie of the sade 
places, the same might then be set uppe of newe with smale 
charges to his lordshippe; whereas now the decaye thereof 
shall be verie costlie and chargeable to be repayred." 

We learn also from Ray's Itinerary (p. 187), that " in Scot- 
land, as late as 1661, the windows of the ordinary country 
houses were not glazed, and only the upper parts of those of 
even the king's palaces had glass, the lower ones having only 
two wooden shutters to open at pleasure and admit the fresh air." 

When desirous in former times of giving encouragement to 
some important manufactures, the government of France was 
induced to declare their prosecution to be nowise incompatible 
with the dignity of aristocratic blood. Early in the fourteenth 
century that government made a concession in favor of glass- 
making greatly beyond this point, decreeing, not only that no 
derogation from nobility should follow the practice of the art, 
but that none save gentlemen, or the sons of noblemen, should 
venture to engage in any of its branches, even as working ar- 



CHAP. I. HISTORICAL NOTICES. 113 

tisans. This restriction was accompanied by the grant of a royal 
charter of incorporation conveying various important privileges, 
under which the occupation became eventually a source of 
great wealth to several families of distinction, whose descend- 
ants have at times attained to some of the highest dignities of 
the state. • 

The good policy is apparent of thus holding forth induce- 
ments to the only parties then qualified by the possession of 
capital, and probably also by their intelligence, to establish 
works upon a scale that could lead either to national advantage 
or individual profit. A middle class of persons, springing from 
the lower orders, have since gradually placed themselves at 
least upon a level in point of intelligence with those of more 
illustrious descent ; and by the exercise of that intelligence, 
conjointly with prudence, have acquired the means for under- 
taking works of magnitude. This altered state of society 
would render such exclusive privileges not merely unnecessary, 
but would make them absolutely pernicious. 

Notwithstanding the marked encouragement just related on 
the part of the French government, some time elapsed before 
the manufactures of France could rival those of Italy. Venice, 
in particular, long excelled in the quality of its mirrors and 
drinking-glasses, with which the manufacturers of that city 
supplied the rest of Europe. The most considerable of their 
glass-houses were established at Murano, a village situated a 
short distance from the city. 

During the ministry of the celebrated Colbert, some French 
artists, who while residing in the Venetian state had acquired 
a knowledge of the processes used at Murano for the making 
of plate glass, returned to France in the hope of profitably pur- 
suing the manufacture in their native country. Such an event 
falling in with the views of Monsieur Colbert, who was anxious 
by every means to extend the useful arts within the kingdom, 
these artists were in the year 1665 established with privileges 
at Tourlaville near Cherbourg, and an advance of money was 
made to them from the public coffers to assist in the formation 
of their establishment. The plates made by this company were 
blown, after the system used in the Venetian manufactories. 

It was not until 1688 that the beautiful art of casting plates 
of glass was invented by a manufacturer named Thevart, who, 
obtaining a patent for the invention to continue in force during 
thirty years, established a company and erected works in Paris, 
where plates were cast of the then extraordinary dimensions 
of eighty-four inches long by fifty inches wide, a size which 
excited universal astonishment and admiration. The expense 
of conducting such a manufactory in the metropolis was, how- 

K2 



114 MANUFACTURE OF GLASS. CHAP. I 

ever, so great, that the establishment was transferred to St] 
Gobain in Picardy, where the undertaking was prosecuted, noi 
without considerable opposition from the more ancient asi 
ciation. 

To accommodate the disputes between these rival establish- 
ments, Thevart's company was bound not to cast any plates 
whose dimensions should be less than sixty inches in lengtl 
and forty inches in breadth. The largest piece that had then| 
been produced by blowing did not exceed fifty inches in its 
largest dimension. This arrangement failed to produce har- 
mony between the rivals ; but in 1695 that end was effectually 
answered by uniting both companies under the same charter — 
not however, as the issue proved, to their mutual advantage ; 
■ — for, possibly owing to the want of the salutary spur of com- 
petition, the company declined in prosperity with such rapidity, 
that in two years from the junction the united body was in a 
state of insolvency, obliged to discharge most of its workmen, 
and to abandon many of its furnaces. 

No blame can be charged upon the French government for 
the protection and privileges afforded to these companies. It 
is probable that without some immunities neither of the estab- 
lishments could at that early period have been undertaken. 
The instances however are rare, and the circumstances whereby 
they have been attended peculiar, in which joint-stock trading 
companies have been prosecuted to advantage. The causes of 
this fact are not difficult of explanation. It is seldom that the 
personal interest of those to whom the particular management 
is intrusted is sufficiently strong to insure the requisite amount 
of attention, or the proper degree of pecuniary watchfulness, 
if even the still more unfavorable condition does not arise 
wherein private advantage is opposed to the general prosper- 
ity, and it is sought to conduct the operations rather with a 
view to individual profit than to the common advantage. 

In the following year a new association was formed out of 
the ruins of the old company, under the management of An- 
toine d'Agincourt, who re-engaged the discharged workmen, 
and by the prudence of his arrangements conducted the affairs 
with considerable profit to the adventurers. 

Blaneourt, in his "Art de la Verrerie," relates as the mode 
in which the casting of plates of glass was discovered, that a 
person who was melting some of this material in a crucible ac- 
cidentally spilt it while fluid upon the ground. The metal ran 
under one of the large flag-stones wherewith the place was 
paved, which obliged the workman to take up the stone in order 
to recover the glass. He then found it in the form of a plate, 
such as could not be produced by the ordinary process of blow- 



CHAP. I. HISTORICAL NOTICES. 115 

ing. The man's attention being roused by this fact, he was un- 
able to sleep ; and conceiving at once the superiority of this 
method for forming mirrors, he immediately commenced exper- 
imenting ; and before the day appeared had proved the practi- 
cability of the improvement which the purest chance had thus 
placed within the sphere of his observation. This occurrence 
is said to have arisen 200 years before it was related by Blan- 
court, whose treatise is dated in 1698. It cannot therefore have 
any reference to the then recent proposals and performance of 
Thevart. 

The manufacture of flint glass was first begun in England in 
he year 1557, at Savoy House in the Strand, and in Crutched 
Viars. In 1635 Sir Robert Mansell obtained a monopoly for 
making this kind of glass, in consideration of his being the first 
aerson who employed pit-coal instead of wood in his furnaces. 
The art could not at this time have reached any great degree 
of perfection, as permission was further conveyed by the patent 
for importing drinking glasses of fine quality from Venice, and 
another half century elapsed before this country became inde- 
pendent of foreign supply for such articles. 

The second duke of Buckingham has the merit of much im- 
jroving the manufacture of British glass by means of certain 
Venetian artists whom he brought to London in 1670. Three 
years later than this period, the first plates of English glass 
were made at Lambeth under the auspices of the same noble- 
man. The violence of party spirit which characterized that 
age should lead us to receive with caution all estimates of char- 
acter which we may find recorded by contemporary biographers. 
Although there was unquestionably much of vice and profligacy 
in the general conduct of this favorite of a vicious and profli- 
gate master, we may yet hesitate to believe that the man who 
could apply himself to the study of letters, and who, in the 
manner above related, interested himself in promoting the use- 
ful arts of life, could at the same time be so utterly depraved 
both in mind and in heart as the page of history has repre- 
sented. 

The first English establishment of magnitude for the casting 
)f plate glass was undertaken in 1773. A respectable body of 
gentlemen at that time obtained a royal charter of incorpora- 
ion, the privileges of which were confirmed to them by act of 
mrliament, under the style of " The Governor and. Company 
»f British Cast Plate Glass Manufacturers;" and having sub- 
cribed a capital or joint stock in eighty shares of five hundred 
»ounds each, constructed works of considerable extent at Ra- 
enhead, near Prescot, in Lancashire. This undertaking, the 
nly one of the kind existing in this country, and rivalled by 



116 MANUFACTURE OF GLASS. CHAP. I. 

none but that of St. Gobain in France, is still prosecuted with 
success ; and some description of its operations will be found in 
a future chapter of this volume. 

It is deserving of remark that the Chinese, whose early pro- 
ficiency in the sister art of manufacturing porcelain was so 
long unrivalled in Europe, have yet no practical knowledge of 
glass making, and that even now there does not exist, though- 
out that extensive empire, a single glass-house which is proper- 
ly deserving of that name. Glass working is indeed practised 
at Canton ; but the art is there wholly confined to the rernanu- 
facture of old or broken glass of foreign make, which is melted 
and either blown or moulded into new forms. 

A similar remark may be applied to the inhabitants of Hin- 
dostan. Dr. Tennant informs us that " before the arrival of the 
Europeans, there was not a house in all India furnished with 
glass windows,"* although there are not many climates where- 
in such an employment of glass is more conducive to comfort. 
The knowledge which the Hindus then possessed of the art of 
making this material was limited to the manufacture of trinkets 
and trifling ornaments ; in fact, their inability to construct fur- 
naces of power sufficient to melt together the ingredients of 
which it should be composed rendered it impossible for that 
people to apply themselves to the manufacture for any more 
useful purpose. ' " Of its adaptation to optical purposes they 
were so ignorant, as to be astonished and confounded at the ef- 
fects of a common spy-glass."t 

Any more minute inquiries into the origin and progress of 
the manufacture of glass would not offer much either of inter- 
est or advantage. The investigation would not connect itself 
with any facts that bear upon the history of commerce, nor 
throw any light upon questions of international policy. The 
general abundance of materials needful for making glass, and 
the facility with which these can be converted — at least into 
articles fitted for common use — are opposed to its becoming 
under any circumstances an object of great moment in foreign 
commerce. The advantage possessed by this country in the 
superior quality and abundance of its fuel does not offer suffi- 
cient compensation for the heavy charges that would attend the 
transport of such bulky articles to countries which themselves 
possess adequate means for prosecuting the manufacture. 

Glass-making, in its various divisions, has long proved a very 
considerable branch of industry in this kingdom ; and although, 
for reasons that will be noticed, our continually growing pow- 

* Indian Recreations, vol. i. p. 325. 

f Mill's History of Brit. India, vol. i. p. 361. Quarto edition. 



CHAP. I. HISTORICAL NOTICES. 117 

er of attaining comforts has not occasioned a corresponding in- 
crease in the quantity retained for domestic use, our colonial 
relations have always insured a very considerable export trade 
to the manufacturers. 

The portion of glass made in Great Britain, and retained for 
home sale, has long been converted into a source of considerable 
national revenue. If articles of domestic manufacture are at 
all legitimate objects of taxation, it does not appear that any 
peculiar objection can be advanced against the extension of the 
system to this particular branch of national industry. The prices 
of such glass utensils as are of most common employment can- 
not be considered great when viewed with reference to their 
beauty and the extreme convenience which attends upon their 
use ; while upon articles of a more costly description the duty 
comprises a comparatively small part of the price. It would 
therefore seem little likely that any material check to the use 
of either description would be caused by even a considerable 
augmentation of the rate of duty. The result has, however, 
always disproved the correctness of such an opinion, as every 
addition which has been made to the rate of duty has occasion- 
ed a most important falling off in the produce of our glass- 
houses. 

In the year 1812 an additional duty was imposed upon glass 
manufactures generally, which, it was estimated by the then 
chancellor of the Exchequer, would produce an augmentation 
of revenue to the extent of 3£8,000Z. The immediate conse- 
quences, however, of this measure, so far disappointed the ex- 
pectations of the minister as to occasion a falling off in the 
quantity manufactured throughout the kingdom of rather more 
than one third, by which means the anticipated increase of rev- 
enue fell short by the sum of 183,000?. 

The general evil tendency of this system of taxation cannot, 
perhaps, be better or more clearly exemplified than by the 
tatement of a few simple facts connected with the manufacture 
of glass. 

The average quantity of all descriptions annually retained 
for home use in the three years ending in 1793 was 373,782 
cwt., while the average quantity consumed during the three 
years ending in 1829, amounted to 364,156 cwt. ; showing an 
mnual decrease in the manufacture of 9626 cwt., notwithstanding 
the great increase of population and the still greater strides in 
civilization made during the interval by all classes of the com- 
munity. 

If the quantities produced during equal periods of three years, 
immediately preceding and following the last and most consid- 
erable advance in the rate of duty, are then contrasted with 



118 MANUFACTURE OF GLASS. CHAP. I. 

each other, the effect appears in a yet more striking point of 
view. The annual average quantity made for home use during 
the three years ending in 1812 was 413,414 cwt, while the 
average of the three following years ending in 1815 was 264,931 
cwt.; showing an immediate falling off of 148,483 cwt., being 
upwards of 35 per cent, upon the larger quantity ; a circum- 
stance which could not fail, among other evils, to bring dis- 
tress and misery upon a considerable number of operative man- 
ufacturers. 

On the other hand, a diminution in the rate of duty on plate 
glass was effected on the 5th of July, 1819, it being then low- 
ered from 98s. to 60s. per cwt. As a consequence, the quan- 
tity manufactured has since been steadily and progressively in- 
creasing. During the three years preceding the abatement, 
the average quantity annually manufactured was 6209 cwt, 
yielding a gross revenue of 30,424Z., whereas the average quan- 
tity made during the three years ending in 1829 amounted to 
15,235 cwt., and the revenue produced was 45,705Z., being an 
increase of more than 50 per cent., derived from a rate of duty 
diminished to the extent of 40 per cent. 

Could any facts more forcibly point out the pernicious ten- 
dency of heavy duties upon articles of domestic manufacture, or 
more clearly indicate the course which it were wise to follow 
in remodelling to as great an extent, and as quickly as is prac- 
ticable, this branch of our financial system 1 

It is much to be regretted that'any circumstances should have 
arisen to delay the execution of the expressed intention of the 
government altogether to remove the duties upon glass. When- 
ever this measure shall be accomplished, it can hardly fail to 
induce such an extension of the manufacture as will prove gen- 
erally beneficial to the community. The abolition of these du- 
ties would be accompanied by the still further advantage of re- 
moving all those vexatious regulations and restrictions under 
which the manufacture is now carried on, and which will cease, 
as a matter of course, when the article is no longer an object 
of revenue. 

It is principally owing to these restrictions that so much for- 
eign glass is now brought into this country in the face of what 
may be considered an amply protecting duty. Foreign manu- 
facturers are allowed to make any and every article out of that 
quality of glass which will most cheaply and advantageously 
answer the end, while our own artists are forbidden to form 
certain objects, except with more costly materials, which pay 
the higher rates of duty. Nor is this restriction only commer- 
cially wrong, since it forms matter of just complaint on the part 
of chemists, that they are unable to procure utensils fitted for 



CHAr. II. INGREDIENTS OF GLASS. 110 

effecting many of the nicer operations connected with their 
science, because the due protection of the revenue is thought 
to require that such utensils shall be formed out of that quafity 
of glass alone which, apart from all considerations of price, is 
otherwise, from its properties, really unfitted for the purpose. 
Relaxations are, indeed, sometimes made on this head in par- 
ticular cases by the commissioners of Excise ; but the trouble 
necessarily attending applications to a public board is greater 
than can be compensated by the trifling money advantage that 
can result in each case to the manufacturer, and the interests of 
science are, consequently, made to suffer. 



CHAP. n. 

ON THE VARIOUS INGREDIENTS EMPLOYED IN MAKING 

GLASS. 

Glass always composed of Silex with Alkali. — Different Descriptions of 
Glass.— Sea-Sand.— Soda and Potash— Pearl-Ash — Barilla.— Kelp.— Wood 
Ashes.— Nitre.— Litharge.— Minium.— Manganese. — Arsenic. — Borax. — 
Chalk. 

Under the general name of glass, chemists comprehend all 
mineral substances, which, on the application of heat, pass 
through a state of fusion into hard and brittle masses, and which, 
if the u broken, exhibit a lustrous fracture. Most glasses are 
transparent also ; and the non-existence of this property is gen- 
erally owing to the presence of some foreign and unessential 
substance. 

The glass of commerce — that beautiful manufacture to which 
the generic name is most commonly applied — does not include 
so wide a range of bodies ; and is always composed of some si- 
icious earth, the fusion and vitrification of which has been oc- 
casioned by certain alkaline earths, or salts, and sometimes with 
the aid of metallic oxides. 

There are five different and distinct qualities of glass manu- 
factured for domestic purposes ; viz. 

Flint glass, or crystal ; 

Crown or German sheet glass ; 

Broad or common window glass 

Bottle or common green glass ; and 

Plate glass ; 

he materials and the processes used in making which form the 
subject of our present inquiry. 

Before commencing the description of any of the manipula- 
ions employed in this interesting manufacture, it will be better 



120 GLASS MANUFACTURE. CHAP. II. 

to give a general account of the different materials used, and to 
point out how the particular qualities of glass are influenced by 
the properties of those various ingredients. 

Each of the five descriptions contains, in common with the 
others, two ingredients, which, indeed, are essential to their 
formation — silex and an alkali. 

The variations of quality, and distinctive differences observ- 
able in glass, principally result from the kind of alkali employ- 
ed, and its degree of purity, as well as from the addition of 
other accessory materials ; such as nitre, oxide of lead or of 
manganese, white oxide of arsenic, borax, or chalk. 

Silex is not equally proper in all its forms for the composi- 
tion of glass. Sea sand, which consists of spherical grains of 
quartz, so minute, as to be qualified for the purpose without 
any preparation except careful washing, is the form wherein 
silex is most commonly used for the purpose in England. All 
sea sand is not, indeed, equally applicable to the glass-maker's 
purpose. That used in this country for making the finer de- 
scriptions of ware is usually obtained, either from the port of 
Lynn, in Norfolk, or from Alum Bay, on the western coast of 
the Isle of Wight. 

The best glass was formerly made with common flints, cal- 
cined and ground in the manner already described, as used in 
the manufacture of pottery, and hence the name which it ac- 
quired of flint glass. The employment of silex in this form is 
now wholly discontinued in glass-houses, as it is known that 
some qualities of sand answer the purpose equally well, while 
the labor and expense of calcining and grinding are saved by 
the substitution. 

Both soda and potash are well adapted to the purpose of ma- 
king glass. They are used in the form of carbonates ; that is, 
holding carbonic acid in combination with themselves as bases. 
The acid flies off during the progress of the manufacture, and 
the result is a compound of silex and alkali. 

As already stated, the quality of glass is influenced by the 
degree of purity of the alkali. For making the finest flint 
glass, pearl-ash, which is potash in a purer form, must be used. 
The alkali must previously be still further purified by solution 
and subsidence, and then evaporating the fluid to dryness. By 
this purification a loss is sustained, amounting to between 30 
and 40 per cent, in the weight of pearl-ash. Coarser kinds of 
alkali, such as barilla, kelp, or wood-ashes, which are combined 
with many impurities, are employed for the production of infe- 
rior glass. Complete fusion and vitrification are accomplished 
by these means, the impurities even being of a nature to assist 
towards the production of these effects. The green color im- 
parted to glass, is produced by the iron, which is present in a 



CHAP. II. INGREDIENTS OF GLASS. 121 

greater or less degree in these courser alkaline substances. 
Barilla, when sufficiently cheap, is always chosen preferably to 
wood-ashes or kelp. The recent abatement of the import duty 
levied upon this article of commerce will, therefore, probably 
tend to the increased consumption of barilla in glass-houses. 

A very small proportion of nitre is used in the composition 
of glass, to occasion the destruction of any carbonaceous mat- 
ter which may exist in the ingredients. This salt must be 
added previous to the fusion of the glass. At a degree of heat 
much below that of the furnace, nitre will decompose, giving 
out much oxygen, and maintaining such metallic oxides as 
may be present in their highest state of oxygenation. It is 
thus of use in fixing arsenic, the volatile property of which in- 
creases as it approaches the metallic state. 

Oxide of lead, in the form of either litharge or minium, is 
essential to the making of flint-glass, into the composition of 
which it enters very largely. This metal acts, in the first 
place, as a most powerful flux, promoting the fusion of all vit- 
rifiable substances at comparatively low temperatures. It is 
also permanently beneficial in imparting highly valuable prop- 
erties to the glass of which it forms a part. This, by its means, 
is rendered much more dense ; has a greater power of refract- 
ing rays of light ; possesses more tenacity when red-hot, caus- 
ing it for that reason to be more easily worked ; and is render- 
ed more capable of bearing uninjured sudden changes of tem- 
perature. On the other hand, glass, into the composition of 
which much lead has entered, is so soft as to be easily scratch- 
ed and injured if rubbed against hard bodies. Such glass is 
also improper as a recipient for many fluids which are of an 
acrid nature, by which it would be corroded and destroyed. 
Another great inconvenience attending the use of lead is this, 
that it does not become intimately enough united with the 
other components for the whole mass to assume an uniform 
density. It will almost always happen, that the glass at the 
bottom of the pot contains a larger proportion of litharge than 
that above. This inequality of density is continually increas- 
ing as the contents of the pot are diminished by the workman ; 
and it is thence impossible to withdraw from it any two por- 
tions whose densities shall agree.* 

* Mr. Faraday has stated, in his paper on the manufacture of glass for op- 
tical purposes, which appeared in the Philosophical Transactions for 1830, 
that he found, on examining "pots containing glass not more than six 
inches in depth, made from the usual materials, and retained at a full heat 
for twenty-four hours," the following differences of specific gravity be- 
tween the glass taken from the bottom and surface of the pots : — 
Top, - 338 330 328 321 315 373 385 381 331 330 
Bottom, 4 04 3 77 385 3 52 380 4 63 474 475 399 374 

L 



122 GLASS MANUFACTURE. CHAP. II. 

Monsieur Guyton Morveau has related a very curious exem- 
plification of this fact, which once occurred to himself when 
experimenting in conjunction with Monsieur de Buffon in the 
plate-glass manufactory near Langres.* Remaining in the cru- 
cible was a portion of flint glass in fusion, composed of thirty- 
two parts powdered crystal, thirty-two parts minium, sixteen 
of soda, and one part nitre. To this was added the requisite 
quantity of the ingredients commonly employed for forming 
plate-glass in the manufactory, and the whole was melted to- 
gether in the furnace. When the mass was sufficiently refined 
it was laded into the cistern, cast on the copper table in the 
usual manner, and transferred to the annealing furnace. Its 
quality being subsequently submitted to examination, the plate 
was found to be composed of two distinct and perfectly level 
strata through the whole mass, the lower stratum occupying 
about one third of its thickness. 

So complete an instance of the precipitation of the denser 
through the lighter portion is not elsewhere to be met with in 
the records of glass-making : its occurrence in this particular 
occasion should probably be referred to the active agency of 
some cause which escaped the observation of the two philoso- 
phers. 

It is a general effect of this inequality, that the glass, when 
wrought, appears waved ; a defect which is particularly incon- 
venient in that which is intended for the construction of opti- 
cal instruments. Glass is also fusible at lower temperatures 
according to the proportion of lead which it contains. This 
quality, which would be mischievous for some purposes, is, on 
the contrary, beneficial for others. It is often essential to 
chemists that they shall be able, during the progress of their 
experiments, to bend the tubes with which they are operating. 

Black oxide of manganese has long been used for clearing 
glass from any foul color which it might accidentally possess 
through the impurity of the alkali employed, and in particular 
from that green tinge which marks the presence of iron. This 
property of manganese, when in the form of an oxide, occa- 
sioned it to be anciently known as glass soap, a name which 
very accurately describes its use. The circumstances attend- 
ing the employment of this substance in glass-making are of 
rather a curious nature. When added in a moderate propor- 
tion to any simple glass, it imparts a purple color ; and should 
its quantity be much increased, this color is deepened until the 
glass becomes nearly black. If, while the mass thus colored is 
still m fusion, either white arsenic, or charcoal, or other carbo- 
naceous matter be added, an effervescence is seen to follow, 

* Ann. de Chim. vol. Ixxiii. p. 113. 



CHAP. II. INGREDIENTS OF GLASS. 123 

and the color becomes gradually more faint until it altogether 
disappears, and the glass is rendered clear and transparent. 
Provided the green hue which it is desired to counteract be 
considerable, the application of a very small quantity of manga- 
nese is not followed by any sensible tinge of purple ; but the 
moment that the proportion is more than sufficient for the pur- 
pose, this color immediately appears, and must be corrected. 
This correction is performed in a very simple manner in the 
glass-house, by thrusting into the pot of melted glass a piece of 
wood, which, becoming charred by the heat, causes the purple 
again to vanish; while a slight effervescence as before de- 
scribed, and the escape of numerous bubbles of air, are plainly 
perceptible. If nitre be then added, the purple color will be 
restored. 

The reason for these changes it is not difficult to explain. 
The oxide of manganese imparts a purple color, only when in a 
state of high oxygenation. When brought into contact with 
carbonaceous matter, it is partially deprived of its oxygen, and 
loses its coloring property. The air-bubbles which escape con- 
sist of carbonic acid gas, which is disengaged by the action of 
the charcoal on the oxide of manganese. The effect which 
follows upon the introduction of nitre is of a contrary nature. 
When made of a red heat this substance gives out oxygen in 
great abundance, and the manganese being thus reinvested with 
the oxygen of which it was deprived by the charcoal, resumes 
with it the coloring property. 

Another advantage attending the use of oxide of manganese 
results from its property of powerfully assisting in the fusion of 
earthy bodies. It also gives considerable density to glass, but 
the same disadvantage accompanies its use as already has been 
noticed with regard to litharge. Having from its greater spe- 
cific gravity a tendency to settle towards the bottom of the pot, 
the glass by this means varies in density throughout its sub- 
stance, in addition to which circumstance the manganese acts 
injuriously upon the pots by corroding them at the bottom. 

One of the uses of white oxide of arsenic has already been 
described, that, namely, of correcting the coloring effects of 
manganese. It is also a very powerful flux, and a great tempt- 
ation to its use is found in its cheapness. It should, however, 
be employed with moderation. If a considerable time be not 
allowed for its intimate incorporation with the other ingredients 
of the glass, this will appear clouded or milky ; a fault which 
will afterwards increase with the lapse of time. An excessive 
quantity of arsenic likewise occasions the glass to become grad- 
ually soft and to decompose, for which reason the employment 
of drinking-vessels in this condition is unsafe. 



124 GLASS MANUFACTURE. CHAP. II. 

Another, and a harmless, application of arsenic in glass- 
making is, when it is introduced into the fused mass in order to 
dissipate any carbonaceous matters which result from defects 
in preparing the alkali. In this case, small lumps of white ar- 
senic are intimately blended with the mass by stirring. The 
great heat causes it at once to unite with and to carry off the 
carbon in a volatile form, leaving the glass entirely free from 
carbonaceous matter, and nearly so from arsenic. 

Borax is used in preparing only the finest descriptions of 
glass : its employment is, indeed, principally confined to plate 
glass. It is too expensive to admit of its forming part in the 
composition of common descriptions, although its use in all 
cases would be desirable, as its efficacy in promoting the fusion 
of verifiable substances is unrivalled. When the borax has been 
introduced, the compound is caused by it to flow with great 
freedom, and to be without specks and bubbles, which would 
impair both its beauty and utility. Should the alkali employed 
prove deficient in strength, a small portion of this salt will serve 
as an effectual remedy. 

Lime in the form of chalk is useful as a very cheap flux. It 
is also beneficial in facilitating the operations of the workman 
in fashioning glass, and it has the property of diminishing its 
liability to crack on exposure to sudden and great variations of 
temperature. Chalk can only be used sparingly, however, in 
the glass-house, as the escape of carbonic acid causes the in- 
gredients in the pot to swell considerably during the fusion. 
The presence of lime in any excessive degree would also occa- 
sion the rapid destruction of the pots, upon the substance of 
which it acts with considerable energy. Glass wherein lime 
exists in excess is also rendered cloudy, although the mass while 
in fusion appears perfectly pellucid. Not more than about six 
per cent, of lime can be added without risking this defect. 



CHAP. in. FURNACES, 125 

CHAP. HI. 

ON THE CONSTRUCTION OF FURNACES, ETC. 

Stability of Furnace Essential.— Fritting Furnace, or Calcar.— Its Use.— 
Working Furnace.— Double Furnace.— Proportionate Dimensions of Fur- 
nace and Pots.— Wood-Furnaces. — Comparative Consumption of Fuel in 
Wood and Coal Furnaces. — Annealing Oven. — Lier-Pans. — Glass-Pots. — 
Their Formation and Seasoning. 

It is essential to the well conducting of the operations of 
glass-houses that their furnaces should be well and substantially 
built of the best materials, and according to the most approved 
construction. 

Monsieur Loysel was so deeply impressed with the necessity 
of devoting the greatest degree of attention to this branch of 
the art, that nearly one half of his clever treatise " Sur l'Art de 
la Verrerie" is occupied with its details. This author not only 
gives instructions for the choice of materials proper for con- 
structing crucibles and furnaces ; but also points out the form3 
which will be found most convenient and advantageous. 

In this country, and since the appearance of the work of M. 
Loysel, those operations connected with the useful arts which 
depend upon the agency of heat have become much better un- 
derstood than formerly, so that principles for the right attain- 
ment of which it was then necessary for individuals to search 
and inquire, and frequently even to experiment, are now be- 
come matters of every-day practice. It cannot, therefore, be 
necessary to imitate that author in all his lengthened initiatory 
directions for the digging and purifying of clay — in his descrip- 
tion of the qualities that should determine our selection of this 
material, or in the detail of mechanical arrangements that will 
prove most efficacious in giving durability to furnaces.* All 
these particulars may safely be committed to the skilfulness of 
the professional builder. 

Some other points there are, however, connected with this 
subject, wherein a greater degree of knowledge than is at 
present possessed is indeed desirable. To persons who have be- 
stowed the smallest attention upon the phenomena of heat and 
combustion it can scarcely fail to appear that science has yet an 

* In stating the degrees of consistence of the clay most proper for the fur- 
naces in different parts and stages of their construction, Mr. Loysel points 
out a simple method of ascertaining the attainments of these degrees, which 
has the advantage of being easily accomplished by any workman. It consists 
in dropping a leaden ball of a given weight from a determinate height upon 
the mass, which should be of that density which will allow the ball, by the 
force of gravitation acquired in its descent, exactly to bury itself in the clay. 

L2 



126 GLASS MANUFACTURE. CHAP. Ill, 

ample field for research there open to her investigations, and 
that the arts have still to look for further and most important! 
benefits at the hand of philosophy. 

The whole operations of the glass-house depend upon the sta-l 
bility of its furnaces. In their original structure the prudent 
manufacturer will, therefore, not hesitate to avail himself of the 
assistance of the ablest builders, and to employ materials which 
are best qualified by their density and infusibility for resisting 
the action of violent and long-continued heat. No present sa- 
ving in the cost of construction can at all compensate for the 
expense and interruptions occasioned by the necessity for fre- 
quent repairs, and still less for the losses of time, labor, and ma- 
terials, that would accompany casualties, the chances of which 
would be multiplied by want of proper attention to the matters 
here pointed out. An equal, and perhaps even a greater degree 
of judgment is required for the selection of materials proper to 
form glass-pots or crucibles, since these have to withstand the 
action of heat in as violent a degree as any part of the furnace, 
and are additionally exposed to injury from the solvent property 
possessed by some of the materials, for the fusion of which they 
are employed. These pots are therefore made of the most re- 
fractory, that is, the least fusible, materials, and are fashioned 
with every possible attention to their strength. 

Three different kinds of furnaces are employed in the manu- 
facture of glass. One, which is called the calcar, a name cor- 
rupted from the French word calquaise, is used for that calci- 
nation of the materials to which they must be subjected previ- 
ously to their complete fusion and vitrification. This process, 
which is called fritting, a term likewise borrowed from the 
French, is used for various reasons. In the first place, it expels 
all moisture from the materials, the presence of which would 
hazard the destruction of the glass-pots. Next it drives ofi^ 
either wholly or in great part, the carbonic acid gas from the 
chalk and alkalies employed, by which means the swelling of 
ingredients in the pots is either prevented, or moderated within 
safe limits. This calcination has the further advantage of de- 
stroying all carbonaceous matters that may be present in the 
materials. But the principal object of previous calcination is, 
that a chemical union may be effected, or at least commenced, 
between the silex, the alkali, and the metallic oxides. Other- 
wise, at the heat of the working furnace, the alkali would fuse, 
and its comparative levity would cause it to take its station at 
the surface, while the other ingredients would subside towards 
the bottom. The uncombined alkali would, in this case, after 
acting upon and injuring the substance of the crucibles, be, in 
great part, volatilized and lost; and a portion of the sand would 



CHAP. III. FURNACES. 127 

Temain unverified, while the glass actually produced would 
contain an excessive quantity of silica. 

These observations do not apply to the preparation of mate- 
rials for making flint glass, the fusibility of which is much 
greater than that of other descriptions, owing to the presence 
of its large proportion of lead. For this reason, manufacturers 
of this kind of glass apply the process of calcination to the sand 
alone, with the view of separating from it all carbonaceous im- 
purities, previous to its admixture with the remaining materials. 

The name of fixed alkalies has been given to soda and pot- 
ash to denote their property of resisting the destructive influ- 
ence of fire. As they are volatilized freely by subjection to a 
red heat, this property cannot, however, be strictly ascribed to 
cither of these substances, and the title must be understood only 
as distinguishing them from other alkaline bodies, which are 
;acted upon by comparatively low additions of temperature. 

The calcar is in the form of an oven about ten feet long, 
.seven feet wide, and two feet high. The coal used in heating 
it is placed in a sort of trough on one side, and the flame is 
made to reverberate from the crown of the oven back to the 
frit. In this operation, care is required to keep the degree of 
heat at all times within that which would melt the materials, 
.and at first below the point whereat the yet uncombined alkali 
twould be volatilized. 

The process must not be hurried at first ; but after two or 
three hours the temperature may be gradually raised until the 
mass becomes pasty. Having been kept in this state during 
three or four tours longer, it is then removed from the calcar 
•and cut quickly, before it has time to harden, into square cakes. 
These are piled away for future use. It is the opinion of many 
glass-makers that frit is improved in quality by age; under 
which impression some among them so manage their operations 
as not to bring their store successively to use until it has been 
prepared for at least twelve months. 

The working furnace is that wherein the frit, when placed 
in the glass-pots or crucibles, is fully melted and converted into 
glass. These crucibles are deep pots, varying in size according 
to the objects of the manufacturer, but sometimes large enough 
for each to contain a ton weight of glass. Twelve of these are 
usually placed, at regular intervals, in the circumference of 
each kiln, their only opening being at the side nearest to the 
wall of the kiln, in which they meet with corresponding open- 
ings, so that the pots can be readily charged, and their contents 
a,s readily removed, by the workmen who stand in recesses 
formed by projections of the masonry. The external form of the 
furnace is circular, rising conically from its base and termina- 



128 



GLASS MANUFACTURE, 



CHAP. III. 



ting in a chimney. The interior is dome-shaped, and supported 
on arches. Flues are constructed under these for the admis- 
sion of atmospheric air, which, rising through the fire-bars that 
occupy the centre of the floor of the furnace, the flame and 
heated air are made to envelop the pots, and thence pass on to 
the chimney issuing from the centre of the dome. 

A very important saving in the article of fuel has lately been 
effected in one of the London glass-houses, that of Messrs. Pel- 
latt and Co., by substituting for one of the large twelve-pot fur- 
naces they had been accustomed to use two similarly construct- 
ed, but having only one half the diameter. The circumference 
of these two being together equal to that of the large furnace, 
they are made to contain as great a number of pots, and of the 
same size, as were formerly employed ; while the internal area 
of the two, being together equal to only one half that of the fur- 
nace for which they are substituted, the pots are necessarily 
brought more than before within the ihtensest influence of the 
fire. The same chimney is made to serve for both furnaces, by 
which means the expense attending the alteration has been 
much diminished. 

Fig. I. 




It is said, that the weekly expenditure of coals has been 
lessened, by means of this alteration, to the extent often chal- 
drons. 

The dimensions of the crucibles and furnace should bear 
some relation to each other. If the former, from their diminu- 
tive size, are much below the efficiency of the furnace, a very 
needless expenditure of fuel will be the result ; and should the 



CHAP. III. FURNACES. 129 

crucibles be too large for the power of the kiln, the heat will 
not prove sufficient. In this case, an excess of fluxing materi- 
als must be used in order to form glass, which will be imper- 
fect, according as it is fused below the most beneficial degree 
of temperature. The relative proportions of pots and furnace 
may be somewhat varied according to the power of promoting 
combustion, which partly depends upon construction and situa- 
tion. Loysel recommends, that in general the aggregate area 
of the crucibles should be very little beyond one fourth of the 
area of the furnace. The experience whereon this recommend- 
ation rested was drawn from the use of wood as a combusti- 
ble, which requires a greater space than coal for the develop- 
ment of a given effect. The difference thus arising would, on 
the other hand, be lessened by the necessity which we are 
under for covering the pots ; whereas, if the kiln is heated by 
means of wood, these may remain uncovered, and their con- 
tents will, in consequence, be more efficiently acted on by the 
heat. Loysel states,* as the result of experiments continued 
during a whole year, that the weight of dry beach wood con- 
sumed in a glass-house furnace exceeded the weight of coal 
burnt in the same furnace, and during an equal period, in the 
proportion of 45 to 28. According to Lavoisier, the heating ef- 
fects of wood and coal are in the proportion of 1089 to 600. 

The result of Loysel's experiment should consequently have 
shown similar effects from the combustion of 45 parts by weight 
of wood, and 24*8 parts of coal ; the difference between this 
last quantity and 28 being, probably, the loss consequent upon 
covering the crucibles. 

The openings already mentioned, as serving for the introduc- 
tion of the materials into the crucibles, and for the removal of 
the melted glass, are called boccas. These may be closed either 
wholly or partially, according to the need of the workman, by 
means of movable collars, or, to speak mor# correctly, by tem- 
porary screens made of fire-clay. On either side of each bocca 
is a smaller circular opening, sometimes called a boccarella, 
but more generally by the familiar name of nose-hole, the par- 
ticular use of which will be explained hereafter. 

The annealing oven, or lier, is a long, low, rectangular cham- 
ber, heated at one end, and furnished with numerous shallow 
iron trays, which can be passed easily along the level bottom 
of the chamber. These trays are called lier-pans, or fraiches ; 
which names, together with those of several implements used 
in glass-houses, are evidently adopted from the French. 

As regards the structure of the annealing chamber, there is 
nothing that particularly requires notice, or that will not be 

* L'Art de la Verrerie, p. 72. 



130 GLASS MANUFACTURE. CHAP. III. 

rendered sufficiently clear by the explanation of its use that 
will be given in the following chapter, while describing, in 
their regular course, the consecutive processes of the manufac- 
ture. 

Every glass-house should possess within itself the means of 
making all the crucibles and other earthen utensils that may 
be required for its operations. The conveyance of these from 
any considerable distance would add materially to their cost, 
not only by the mere expense of carriage, but through the 
greater liability to fracture, whereto such unwieldy vessels 
would in that case be subject. 

These crucibles, or glass-pots, should be made with five parts 
of the best Stourbridge fire-clay and one part of old broken 
crueibles ground to powder for that purpose. Great nicety is 
required in mixing these ingredients and in working them to- 
gether, in order to drive out from their substance every particle 
of air, the presence of which would, by its expansion in the fur- 
nace, occasion the immediate breaking of the pots. 
The method invariably pursued for kneading the clay is, 
Fig. 2. that the workman treads on it for a consid- 
erable time with his naked feet, turning it 
over from time to time, so that every part 
may, in its turn, be subjected to the required 
pressure. An attempt was recently made by 
a glass manufacturer to employ machinery 
for the purpose; but after having incurred 
considerable expense, and exerted much in- 
genuity in perfecting his apparatus, this gen- 
tleman has reverted to the old inartificial method, as being deci- 
dedly the best calculated to insure the goodness of his crucibles. 
This attempt at improvement was not relinquished, until the 
losses which were sustained in its prosecution became of seri- 
ous moment. • 

After the crucibles are formed, they are suffered to remain 
for a considerable time in the apartment wherein they were 
made, in order that they may dry equally throughout their sub- 
stance. It is not, indeed, considered prudent to remove them 
from this situation until they shall have been formed for at least 
a twelvemonth. 

For some little time before a pot is put to use, it must be 
placed in an apartment wherein heat can be artificially admit- 
ted, and either raised or lowered at pleasure. It is then re- 
moved for about three days to a furnace particularly appro- 
priated to the baking of pots; and here the temperature, which 
at first is moderate, is gradually increased, until at last it is 




CHAP. IV. FLIWT GLASS. 131 

made nearly as intense as that of the working furnace, for in- 
sertion in which the crucible is then sufficiently fitted. 

With all the skill and care that can be employed in their 
manufacture, these crucibles will frequently break during a 
very early period of their use, and the loss occasioned by that 
means to the manufacturer is in many ways one of very seri- 
ous importance. 



CHAPTER IV. 

ON THE MANUFACTURE OF FLINT GLASS. 

The most beautiful and costly Kind of Glass.— Importance of its duality for 
Optical Purposes.— Experiments for its Improvement— Undertaken by the 
Royal Society— Promoted by Government.— Distinguishing Properties of 
Flint Glass. — To what owing. — Different Compositions. — Process of Melt- 
ing.— Glass-Gall.— Its Use.— Curious Phenomenon.— Implements.— Col- 
lecting Glass on Rod. — Marver. — Paraison. — Blowing. — Re-heating. — 
Elongati ng.—Pontil.— Fashioning.— Detaching.— Removal to Annealing 
Oven.— Moulding. — Annealing.— Why indispensable.— Bologna Phials.— 
Rupert's Drops. 

Flint glass — known in foreign countries under the name of 
crystal — retains among us the title originally imparted by its 
srincipal ingredient, although the use of flint in its composition 
las long since been discontinued. 

This glass is the beautiful and peculiarly refulgent com- 
pound whereof the finest articles designed for domestic use 
or for ornament are made. Of all the vitrified compounds 
that are manufactured, it is the heaviest and the most brilliant ; 
the one most easily fashioned by the hand of the workman, and 
that which has the greatest refractive power. It is also, from 
the nature of its constituent materials, the most costly. 

Vessels of flint glass cannot, however, be properly applied to 
all purposes. If, for instance, they are used to contain car- 
bonate of ammonia, they will very soon become so exceedingly 
brittle, that the very slightest apparent cause will occasion 
pieces to fall out. Common green bottle glass is not liable to 
this objection. 

Were we to judge from the practice of different manufac- 
turers, in bringing together the ingredients that form this com- 
pound, we must believe, that to adhere to any exact proportions 
is by no means indispensable. In almost every different glass- 
house a peculiar recipe is followed, and no two writers upon 
the subject agree in their statement of the exact doses wherein 
any of its components should be used. It is by no means be- 
lieved, however, that these vague proceedings are without in- 
convenience, or that some particular compound might not be 



132 GLASS MANUFACTURE. CHAP. IV. 

discovered and adopted, which, for many purposes, would be 
superior to every other. 

The employment of this species of glass in the construction 
of optical instruments renders every attempt towards its im- 
provement a matter of universal interest and importance. A 
committee of scientific men have been for some years engaged, 
at the expense of government, in a series of experiments, with 
a view to discover some composition by which glass may be 
obtained in large pieces, free from those defects which have 
hitherto circumscribed the power of telescopes within a nar- 
row limit. In such investigations, however, great difficulties 
are to be encountered ; and a long time is as necessary as great 
talents to overcome them. The progress which has been made 
by the committee, though not perhaps so great as the lovers 
of science could have wished, is still as great as the difficulties 
of the subject — even in the most able hands — would have led 
us to hope for, and is sufficient to justify sanguine anticipations 
of future success. 

The properties of flint glass which distinguish it from other 
vitrified substances are owing to the presence of some metallic 
oxide. All metals, when oxidated, will combine with silica 
and alkali to form glass. Few of them are, however, properly 
qualified for the purpose, in consequence of their imparting 
colors to the mass. The oxides of lead and of bismuth are the 
only two which may be used in sufficient quantity without pro- 
ducing this inconvenience ; and as lead is by much the cheap- 
est of these metals, it is always preferably employed in the 
manufacture. An over dose of lead will, indeed, discolor glassy 
imparting to it a tinge of yellow. 

It is essential to the goodness of the glass that no impurities 
or foreign matters should be combined with the lead, and as 
the adulteration of its various oxides is both easily effected, and 
difficult of detection, the glass-maker who does not prepare 
this substance for himself, should make his purchases only from 
persons on whose probity he can rely. Loysel recommends 
the use of minium, as being less susceptible of adulteration 
than the other oxides of lead. English glass-makers more fre- 
quently employ litharge. 

The author just mentioned gives as the composition of crys- 
tal, where coal is employed as fuel, — 

White sand . . . 100 parts. 

Red lead 80 to 85 

Pearl-ash 35 to 40 

Nitre 2 to 3 

Oxide of manganese 0-6 

Where wood is used for the reduction of the ingredients, and 



CHAP. IV. FLINT GLASS. 133 

where consequently, the crucibles may be left uncovered du- 
ring the process, a different mixture is preferred. In this, a 
much smaller proportion of metallic oxide is added ; and the 
reason assigned by M. Loysel for this variance is^that the air, 
having constant , and unimpeded access to the surface of the 
glass, supplies any deficiency of oxygen, while the process is, 
through the more direct application of heat, more quickly per- 
formed, and the glass when manufactured is harder and more 
durable. The proportions given for this compound are, — 

White sand 100 parts. 

Red lead 50 to 60 

Pearl-ash 30 to 40 

Oxide of arsenic 0-75 to 1 

The specific gravity of this glass will not be so great as that 
of the former compound in the proportion of 29 to 32, and its 
refractive power will evidently be smaller also. 

Messrs. Aikin, who, as a matter of scientific research, 
brmerly directed their minds to the consideration of this im- 
portant branch of manufacture, and who, then made many ex- 
periments connected with the art of glass-making, state* that a 
very excellent article may be made from — 
120 parts fine clean white sand ; 

40 well purified pearl-ash ; 

35 litharge or minium ; 

13 nitre, and a small quantity of the black 

oxide of manganese ; 
the superior fluxing power of the nitre supplying, in that 
respect, the difference which exists in the proportion of lead 
between this compound and the first formula of Loysel. To 
introduce so large a dose of metallic oxide as is recommended 
3y the French author produces an inconveniently soft material. 
That the proportion is excessive may well be inferred from the 
fact ascertained by Dr. Priestley, that if a tube of glass so com- 
30unded be made red-hot, and a stream of hydrogen gas be 
passed through it, the whole inner surface will be covered with 
half brilliant black substance, which results from a partial 
reduction of the lead, and moisture will appear at the further 
md of the tube. 

The result of many preliminary experiments made on a re- 
lent occasion by Mr. Faraday, with the object of producing per- 
'ectly homogeneous glass for optical purposes, induced that gen- 
ileman to give the preference to a compound of silica, boracic 
icid, and oxide of lead, brought together in single proportionals, 
md which he therefore designates a silicated borate of lead. 

* Pictionary of Chemistry, vol. i. p. 496. 

M 



134 GLASS MANUFACTURE. CHAP. IV. 

The important aim of Mr. Faraday's inquiries induced him 
to neglect no one particular by which they could be forwarded, 
and he accordingly employed all those chemical means with 
which he is so perfectly acquainted to insure the absolute purity 
of the ingredients which he thus selected. 

The oxide of lead was converted from the state of litharge 
into a nitrate by first washing it and separating the carbona- 
ceous and ferruginous particles, and then placing it in a clean 
earthen vessel, and dissolving in dilute nitric acid, so as to form 
a hot saturated solution. After 18 or 24 hours the crystals 
which had formed were collected, broken up into small parti- 
cles, and repeatedly washed in fresh clear portions of the 
mother liquor, in order to remove any insoluble deposited mat- 
ter. When thus perfectly cleaned, the broken crystals were 
drained, and then dried by being placed in a sand bath and 
constantly stirred, after which they were preserved in glass 
bottles for future use. 

Mr. Faraday was enabled to procure pure boracic acid in 
crystals from the manufacturers, subjecting it in every case, 
however, to careful examination, and testing it by various 
agents to ascertain the absence of impurities. 

Sand from the coast of Norfolk needed no other preparation 
to insure its purity than to be well washed and calcined, and 
this was the only source whence Mr. Faraday drew his supply 
of silica. 

The previous fritting described in the last chapter was 
formerly performed for the manufacture of all kinds of glass ; 
but, as regards the kind under description, is not now 
adopted. The materials are used in a state of greater purity, 
and the process is, on that account, as well as for another 
reason already given, no longer considered advantageous. 

The ingredients having been intimately mixed, are cast, by 
means of clean iron shovels through the side openings, into the 
crucibles; which, previously to this, must be brought to a 
white heat. The pots are filled at once with the mixture ; 
but as the bulk of this decreases materially in melting, a fresh 
portion must be added when this effect has been produced ; and 
this operation is repeated until, by these successive fillings, the 
vessels at length become fully charged with melted glass. Be- 
fore any fresh portion of materials is added, that already in the 
crucible must be completely melted. When this is full, the 
opening through which the charge was introduced is materially 
lessened with wet clay, so that only a narrow hole remains, 
through which the impurities may be removed, and small por- 
tions of the contents' may, from time to time, be drawn for 
examination. 



CHAP. IV. FLINT GLASS. 135 

Immediately upon the materials being placed in the cruci- 
bles, the heat of the furnace is raised to its highest point. The 
contents are soon observed to sink down in the state of a soft 
paste, and ere long become perfectly melted. The glass does 
not, however, immediately thereupon appear transparent, but 
loses its opacity by slow degrees, as a white porous scum, 
known by the name of sandiver or glass-gall, rises through 
the mass and is removed. This scum appears to consist of 
salts, which more or less exist in alkalies, and which salts, hav- 
ing little or no affinity for silex, and being specifically lighter 
than glass, rise to the top. Another foreign substance is some- 
times found at the bottom of the pots, and is removed when the 
glass is worked off. This, which is also called sandiver, is of 
a nature altogether different from the scum before mentioned, 
being a vitrified mass of metallic and earthy impurities. In 
the strong heat of the furnace glass-gall is exceedingly volatile ; 
so that, if not removed as it forms on the surface, it would all 
be dispersed in the form of a dense vapor, very dark at first, 
and growing white by degrees, as the glass becomes purer. 
This vapor is very corrosive, and acts injuriously upon the tops 
of the crucibles. 

Sandiver is purchased by refiners of metals, who use it as a 
powerful flux. It is necessary that the whole of this substance 
should come away before the glass is withdrawn from the pots 
for use, otherwise articles formed with it will appear cloudy, 
and filled with bubbles. A very strong and long continued 
heat is generally required before the whole impurities are dis- 
charged. As the process advances, the glass proves increas- 
ingly flexible, heavier, and less brittle, till at length the glass- 
gall is altogether thrown off, no more vapors rise, the bubbles 
expand, rise to the surface and burst, and the whole is seen to 
be colorless and translucent. 

In this state, vitrification is complete, but the glass is too fluid 
to be fashioned, and for this purpose its temperature must be 
lowered by stopping the draught of the furnace in that particu- 
lar part where the crucible is placed ; the clay wherewith its 
opening was lessened is then removed, and the operations of 
the glass-blower may be commenced. 

When cooled to the heat most proper for its being wrought, 
the glass has lost its perfect fluidity, being of a consistent and 
tenacious mass, soft enough to yield to the slightest external 
impression, yet capable of being bent, pulled, and fashioned into 
all imaginable shapes, without cracking or parting with its te- 
nuity ; so that if in this state it be stretched or drawn out, it will 
preserve the form of a solid fibre, constantly decreasing in its 
diameter, and will not separate until reduced to the merest fila- 



136 GLASS MANUFACTURE. CHAP. IV, 

ment. When no longer heated to redness, glass becomes rigid, 
brittle, and transparent. During the whole time employed in 
working a pot of glass, which varies from five to twenty hours, 
and is sometimes even longer, its consistence should be main- 
tained as nearly as possible at the same point, and to succeed in 
this calls for considerable attention on the part of the work- 
men. 

The contents of all the crucibles do not come into the work- 
ing state at the same moment ; but no injury arises from this 
cause, as glass may remain for a very considerable period in the 
melted state without, in any respect, altering its qualities. The 
fusion and perfect refining of flint glass, as here described, are 
usually completed in about forty-eight hours from the first 
charging of the crucibles. 

In the operations of a glass-house it is, indeed, common, pur- 
posely to manage the vitrifying of the materials so that the con- 
tents of the different crucibles shall be brought to the state 
proper for blowing in succession, that when the glass contained 
in one is all worked up, that in another shall be in perfect 
readiness for use. By this arrangement the workmen experi- 
ence no interruption, and the heat of the furnace is constantly 
maintained, which last is a consideration of some importance ; 
for if through any accident, the temperature be allowed to sink 
in a material degree, considerable expense of time and fuel are 
required for its restoration. 

It is by no means advisable to employ in the formation of the 
same glass vessel materials drawn from more than one cruci- 
ble. Although the original composition may have been alto- 
gether identical, and the fusion of all has been simultaneously 
carried forward in the same furnace, still a minute difference 
may, and generally will, exist in the constituent proportions of 
each mass, arising from an accidental variance of draught, and 
consequently of heat, in different parts of the furnace, whereby 
some crucibles may have been made to part with a larger pro- 
portion of their alkali than others. Any circumstances which 
interfere with the perfect sameness of quality in every part of 
vessels formed of glass renders them more liable to break on 
exposure to sudden changes of temperature, by reason of their 
differing tendencies to expand and contract under such circum- 
stances. 

The implements used by glass-blowers are few in number, 
and exceedingly inartificial in their form and construction. 
The principal one is simply a hollow iron rod or tube, about 
five feet long, upon one end of which the workman collects the 
quantity of melted glass that will suffice for forming the article 
intended. In this operation the rod is dipped into the pot and 



CHAP. IV. FLINT GLASS. 137 

turned about several times. If the size of the vessel requires a 
considerable weight of glass for its formation, the rod is taken 

Fig. 3. 



out and exposed momentarily to the current of air, by which 
means the surface of the glass already collected is sufficiently 
cooled for a fresh portion to adhere, and this proceeding is re- 
peated until enough is collected for the object. 

When the rod thus loaded is withdrawn from the crucible, it 
is held for a few seconds in a perpendicular position, the end to 
which the glass is attached being nearest to the groimd, that by 
its own weight the mass may be lengthened out beyond the rod. 
The next operation is to roll the glass on the flat surface of a 
smooth horizontal iron plate called the marver, a name corrupt- 
ed from the French word " marbre." By this means the par- 
ticles of glass are agglomerated in a cylindrical form, which is 
then called by the workmen a paraison. The workman then 
applies his mouth to the other end of the tube, and blows strong- 
ly through it, so that his breath, penetrating the centre of the 
red-hot glass, causes it to be distended into a hollow globe. The 
pressure of the breath must be continued upon the tube for a 
few seconds to prevent the return of any portion of the air 

Fig. 4. 




through the tube, otherwise the external air being more dense 
than the heated portion confined within, the globe would col- 
lapse : when it has been somewhat stiffened by cooling, this 
accident is no longer to be apprehended. 

M2 



138 GLASS MANUFACTURE. CHAP. IV. 

The globe, which is not made sufficiently thin by this one 
blowing, is then heated anew by being held a little within the 
opening of the furnace ; the breath is again employed as before, 
and so on repeatedly, until the proper size and thickness of the 
globe are satisfactorily attained. 

If the form of the intended vessel requires the globe to be 
elongated, this effect is produced by giving to the rod, while 
the glass attached to it is softened by heat, an alternating mo- 
tion similar to that of a pendulum, or by dexterously making it 
perform a circle swiftly through the air. The tendency to fly 
off from the centre which is thus imparted causes the particles 
to change their relative positions in a degree corresponding with 
the amount and duration of the force employed. 

At this stage another implement, called a punt, or pontil, is 
brought into use. This is a solid iron rod of a cylindrical form, 

Fig. 5. 



smaller and lighter than the tube used for blowing, and conse- 
quently more within the power and management of the work- 
man. Upon one end of this rod a small portion of melted glass 
is collected, by an assistant, from the crucible, and in this state 
is applied to the surface of the globe on the side opposite to that 
where it is already attached to the tube. The two heated sub- 
stances speedily uniting, the glass is detached from the hollow 

Fig. 6. 



rod, by touching it near to their point of contact with a small 
piece of iron wetted with cold water. This occasions the glass 



CHAP. IV. FLINT GLASS. 139 

to crack, so that by giving a smart stroke to the hollow rod, it 
is immediately and safely separated, leaving a small hole at the 
point of rupture. 

The workman now receives from his attendant the pontil 
with the glass vessel attached, and after reheating it at the 
furnace mouth as before, seats himself on a sort of stool provided 

Fig. 7. # 




with arms sloping forward, whereon the pontil is supported be- 
fore him in a horizontal position, the glass being at the man's 
right hand. Thus placed he governs with his left hand the 
movements of the pontil by twirling it to and fro along the arms 
of the stool ; and taking in his right hand an iron instrument, 
called a procello, the blades of which are connected together by 
an elastic bow, in the manner of a pair fig. 8. 

of sugar-tongs, he enlarges or contracts 
the vessel in different places until it as- 
sumes the requisite form. Any supera- c 
bundance of material is cut away by the scissors while the 
glass is red-hot, with as much ease as they could be made to 
divide a piece of soft leather. 

If the article is of a kind, by its size or by the complex na- 
ture of its form, to occupy much time in its manufacture, it 
must occasionally be reheated, as its increasing rigidity makes 
it more difficult of management. 

To insure the requisite regularity in shape and size, the 
workman is provided with compasses and a scale marked off in 
feet and inches. 

The finished article is detached from the pontil in the same 
manner as it has previously been from the blowing tube, by 
wetting it at the point where it is attached, and is then dropped 
gently on a bed of ashes kept at the man's side for the purpose. 



140 GLASS MANUFACTURE. CHAP. IV. 

It is then taken up on a pronged stick, or, when from its shape 
this mode is inconvenient or impracticable, the glass is made 
to rest during the detaching process on a wooden shovel, 
wherein it consequently remains when divided. In either case 
a boy in attendance conveys it without loss of time, and while 
yet exceedingly hot, to the annealing oven. 

If it be required to give to the article any form or pattern 
which is unattainable by«the simple means narrated, a mould is 
provided, into which the glass is placed while it is being blown, 
and where it receives the requisite impression with as much fa- 
cility and faithfulness as wax. 

The process of annealing is one of very great importance ; 
without it, glass would be liable to fly with the smallest change 
of temperature, and would break with the merest scratch or 
touch, or even without any apparent external cause of injury. 
The most reasonable theory which has been proposed in expla- 
nation of this disposition in unannealed glass is, that by its sud- 
den cooling the external particles are forcibly contracted, while 
the inner substance still remains soft and expanded. The two 
portions thus take up positions, in relation to each other, very 
different from those which they would occupy if the contraction 
of the whole had gone forward equally and gradually. By this 
means a constant strain is kept up between the different parts, 
and should a force be applied of a nature to rive any the smallest 
portion asunder, the equilibrium of resistance is deranged, and 
the elastic quality of the glass causes the injury to be felt 
strongly and suddenly, but very unequally, through the whole 
mass. 

This theory appears to receive confirmation from the well 
known and often repeated experiments made with the Bologna 
phial and with Rupert's drops. The first is a phial of ordinary 
shape made of any kind of glass, much thicker at its bottom 
than in its upper portion, and which has been suddenly cooled 
in the air. This phial, from its thickness, will sustain a con- 
siderable blow from any blunt instrument, or will bear unin- 
jured the sudden concussion caused by the fall of a leaden bul- 
let. But if any hard and angular substance, such as a minute 
portion of gun flint or even a grain of sand, be dropped into it, 
the bottom will crack all round and drop off. In performing 
this experiment, if the glass be very brittle and the substance 
dropt upon it be very hard and sharp — a cut diamond for in- 
stance — this has been seen to pass through the thick bottom 
with apparently as little resistance as would be offered by a 
cobweb. 

The greater comparative thickness of the bottom is an indis- 
pensable quality of these Bologna phials, and the more consid- 



CHAP. IV. FLINT GLASS. 141 

t 

erable this disproportion is made, the more easily will the dis- 
ruption be effected. Some of these vessels have been struck 
by a wooden mallet, and were uninjured, notwithstanding the 
force applied was sufficient to drive a nail into most kinds of 
wood ; and yet the glasses broke readily when a small shiver 
of flint weighing only two grains was gently dropt within them. 
Flint being very hard, and its angles when fractured extremely 
sharp, its points of contact with the glass are exceedingly 
small, so that the effect produced by even so very minute a 
portion of this substance will be comparatively greater than 
would accompany the blow given by a much larger but softer 
and less angular body, and which for these reasons would di- 
vide the shock between a greater comparative number of parti- 
cles of the glass. 

Another theory has been proposed in order to account for this 
singular property in certain fonns of unannealed glass. It has 
been imagined that the sudden cooling of glass may occasion it 
to be more electric than is consistent with the cohesive attrac- 
tion of its particles, and that the sudden setting in motion of 
the electric fluid which glass contains, may occasion throughout 
the substance a propagation of the motion of that fluid, which 
will go on accumulating within itself a force too great to be at 
length resisted. 

This theory is by no means free from difficulties, yet it seems 
to derive support from a fact which was developed in the course 
of some experiments made before the Royal Society, in which 
glass vessels, the thick bottoms of which were only slightly 
rubbed by the ringer, broke after the interval of half an hour 
had occurred from the time of rubbing. 

Rupert's drops are small solid pieces of common green glass, 
which have been dropped while red-hot into cold water, and 
which are thus caused to take the form of rounded lumps elon- 
gated into a kind of tail. The spherical part will bear very 
rough treatment without injury ; but if the smallest portion of 
the tail be broken off, the whole article instantly bursts into a 
countless number of fragments, so minute as to produce only a 
slight stinging sensation in the hand by the sudden disruption. 
If one of these drops is immersed in a phial or tall glass filled 
with water, and its end be broken off with a pair of pincers, the 
bulb will be rent so suddenly and with so great a force as will 
infallibly break the vessel wherein it is contained. The stoutest 
wine or beer bottle would not be strong enough to withstand 
the shock. 

Messrs. Aikin completely destroyed this property in drops of 
this kind and in Bologna phials, by heating them to redness and 
then allowing them to cool gradually as in the annealing oven. 



142 



GLASS MANUFACTURE. 



CHAP. IV 



Not only was their quality of bursting corrected by this treat-l 
ment, but the particles of glass were made to assume a closer 
union among themselves, which fact was proved by the acquire- 
ment of a sensible increase in their specific gravity. 

The internal form of an annealing oven has been already de-l 
scribed. Articles newly made are placed on the shallow trays 

Fig. 9. 




previously mentioned, in the part of the oven most exposed to 
the heat of the fire, which, it will be remembered, is kindled 
under one end only. Each one of these lier pans or fraiches, as 
it is filled, is pushed forward in the oven, towards the colder 
end, to make place for a fresh tray, until the articles, at length 
and in succession, reach the farthest extremity of the oven, 
whence they are taken, but little warmer than the temperature 
of the atmosphere. 

By the gradual manner in which they have parted with their 
heat, time has been allowed for the regular contraction of the 
whole into an uniform and consistent substance. 

In glass-houses where objects of various magnitudes and de- 
scriptions are made, two or more of these annealing ovens are 
usually attached to each working furnace. Pieces which are 
large, and of considerable substance, require that the oven in 
which they are annealed should be made much hotter than, is 
necessary for thinner and smaller pieces. Glass which is after- 
wards to pass through the hands of the cutter is always made 
of considerable thickness, and requires not only that the heat 
of the oven should be very considerable when it is first inserted, 
but that it should be withdrawn from this heat very gradually ; 
while, on the contrary, such articles as are very thin may be 
placed at first in a much more moderate temperature, and may 
be removed altogether at the expiration of a few hours. 



CHAP. IV. FLINT GLASS. 143 

It is impossible by written explanations to impart beyond a 
very faint idea of the truly curious and interesting operations 
of the glass-blower. This difficulty does not arise from any 
complexity in the manipulations. Although, in common with 
nearly all the manual arts, these call for long practice to insure 
proficiency, they are yet exceedingly simple in their nature. 
But there is something more than ordinarily striking — perhaps, 
even, it may be said fascinating — in watching the progress 
through which a substance, in its usual state rigid and brittle to 
a proverb, passes, by rapid conversion, from a glowing and 
shapeless lump to a perfect article of most elegant manufac- 
ture. The absolute control which the workman exercises over 
its form and substance ; the perfect ease and security where- 
with he pulls, and twirls, and divides, and joins, a matter which 
we are accustomed to handle with only gentleness and care ; 
never fail to excite a high degree of admiration even in those 
who have had frequent opportunities for witnessing the pro- 
cesses. 

The amusement to be derived from watching the operations 
employed in many branches of manufacture is probably much 
greater than would be imagined by persons who have not so in- 
dulged their curiosity ; and among these manufactures, al- 
though there are doubtless many that call in a higher degree 
for our admiration as proofs of the genius and perseverance of 
man, there is not one calculated to afford, for the time, more 
gratification than the operations of a glass-house. 



CHAP. V. 

ON THE MANUFACTURE OF CROWN GLASS, BROAD GLASS, AND 
BOTTLE GLASS. 

Description of Crown Glass.— Harder than Flint Glass.— More difficult to 
Fashion.— Its Composition.— In France.— In England.— Fritting.— Cullet. 
—Refining.— Sulphate of Soda.— Vegetable Charcoal.— Gathering.— Blow- 
ing.— Reheating.— Flattening.— Transferring to Pontil.— Twirling.— Ex- 
panding.— Opening.— Annealing.— Nice Regulation of Temperature re- 
quired in this Process.— Qualities of Crown Glass.— German Glass.— 
Broad Glass.— Inferior to Crown Glass.— Its Composition.— Preparation. 
—Working.— Bursting.— Opening.— Annealing.— Bottle Glass.— Manufac- 
ture checked by Increase of Duty.— Composition.— Restrictions as to Ma- 
terials.— Their bad Tendency.— Superiority of Bottle Glass for certain 
Purposes.— Materials employed in France.— At Newcastle.— Fashioning. 
—Moulding.— Experiments suggested by Count Chaptal.— Klingstein.— 
Volcanic Granite. 

The name of crown glass is given to the best kind of glass 
commonly used in making windows, and for like purposes. In 
the composition of this material, no lead or metallic oxide en- 



144 GLASS MANUFACTURE. CHAP. V. 

ters as a fluxing agent. A small quantity of manganese is fre- 
quently used, and sometimes also a minute portion of oxide of 
cobalt ; but the object of these additions is the correction of a 
faulty color in the glass, arising from impurities in the sand and 
alkali. This kind is, therefore, much harder than flint glass, 
and would consequently be more difficult to fashion, if it were 
desired to give it any other form than that of a plane surface. 
The composition of crown glass varies considerably. Loysel 
has given several different recipes for its formation. That 
which he most recommends, stating that it is employed at the 
extensive works of St. Gobain, consists of 

Fine white sand 100 parts. 

Carbonate of lime 12 

Carbonate of soda, calcined, 45 to 48 

Clippings of crown glass . . 100 ; 
with such additions of manganese and oxide of cobalt, as may 
be required to correct impurities and remove the color which 
they occasion. By proper carefulness in selecting and purify- 
ing the ingredients, the employment of these metallic bodies is 
rendered unnecessary. 

Crown glass is generally made in France of 100 parts of 
fine white sand, 50 to 65 parts potash, 6 to 12 parts dry slaked 
lime in powder, and from 10 to 100 parts of broken glass of 
similar quality : this composition is frequently employed in 
that country for the manufacture of common drinking vessels, 
as well as of window panes. 

In England, this material has usually been composed of fine 
Lynn sand, kelp, and slaked lime ; the proportions of these in- 
gredients varying according to the quality of the kelp, some 
kinds of which contain a greater amount of alkali than others. 
That from Orkney is considered to be the best, not only on this 
account, but also because the glass which is made of it proves 
of a better color than where Scotch or Irish kelp is employed. 
The proportions when the kelp is of the best quality are, 
Fine sand .... 5 bushels or 200 pounds' weight, 

Ground kelp . 11 330 

Slaked lime 15 ; 

which ingredients are fritted in the calcar as already described, 
preparatory to their fusion. When put into the crucible, about 
half its weight of broken glass, or, as it is called in the manu- 
factory, cullet, is added to the frit. This compound requires to 
be kept in fusion at a high degree of heat during thirty-five to 
forty hours, in which time an intimate union of all the parts 
takes place ; the glass refines itself by throwing off all its san- 
diver, and becomes perfectly transparent. It is not advisable to 
use a larger proportion of broken and refuse glass than that 



CHAP. V. CROWN GLASS. 145 

just mentioned, because, by its long exposure to heat when in 
fusion, glass is made to give up a portion of its alkali, becoming 
harsher and less fusible. The quantity of glass usually em- 
ployed is serviceable by sooner bringing the pot to a working- 
state ; but any larger quantity would, for the reason just stated, 
sensibly alter the quality of the whole contents of the crucible. 
The fragments, before they are used, are first heated, and then 
suddenly plunged into cold water, which renders it easy to re- 
duce them to powder. 

A very superior quality of crown glass is made by the mix- 
ture of 

120 parts by weight of White sand, 

60 Purified pearl-ash, 

30 Saltpetre, 

2 . . s . . . Borax, 

1 Arsenic. 

If the color should prove yellow, this is corrected by the ad- 
dition of a small quantity of manganese. 

Another composition, cheaper than the foregoing, consists of 
120 pounds of White sand, 

50 Unpurified pearl-ash, 

20 Common salt, 

10 Saltpetre, 

4 Arsenic, 

and 3 ounces of Manganese. 
This produces glass of a good and useful description, much em- 
ployed in the manufacture of apothecaries' vials. 

The late M. Gehlen, who was well experienced in the art 
of glass-making, composed crown glass of the following ma- 
terials*: — 

Sand 100 parts. 

Dry sulphate of soda . . 50 
Quick-lime in powder . 17 to 20 

Charcoal 4. 

In this case the sulphuric acid in combination with the soda is 
decomposed by the charcoal, and driven off during the fusion, 
leaving the soda to unite with the sand. M. Gehlen made 
many experiments to ascertain the effects of various combina- 
tions with sulphate of soda, and found that this salt could be 
used without the addition of any other saline flux. If mixed 
with only sand, the vitrification was very imperfect even after 
long-continued heat. The addition of lime caused it to suc- 
ceed better, but the time and fuel required were still excessive. 
When, however, by the addition of vegetable charcoal, the sul- 

* Annates de Chimie et de Physique. Fevpier, 1816. 

N 



146 GLASS MANUFACTURE. CHAP. V. 

phuric acid was decomposed, and the powerful affinity de- 
stroyed, which prevented the soda from acting on the sand, vit- 
rification was produced hoth perfectly and quickly. If used in 
any other proportions than those above mentioned, M. Gehlen 
found that the fusion was accompanied by disagreeable sulphur- 
ous odors, and by an extraordinary swelling over of the mate- 
rials. The decomposition of the sulphate of soda may be 
effected with equal advantage, either during or before vitrifica- 
tion, according as the choice of the manufacturer may be influ- 
enced by local circumstances. 

When the materials are properly fused and refined by the 
removal of all the glass gall, the workman commences his 
blowing operations in exactly the same manner as has already 
been described in the process for making flint glass. By re- 
peated dippings of the iron tube into the crucible, he gathers 
as much glass upon its end as experience teaches him will suf- 
fice for the formation of a sheet of glass of the usual size, and 
which generally weighs from ten to eleven pounds. This lump 
he allows to project beyond the extreme end of the tube ; and 
first rolling it on the iron plane before described, to give the 
glass a cylindrical form, he commences blowing, when it as- 
sumes the shape of a pear. A fresh heating and a second blow- 
ing enlarge its dimensions, and render its shape more globular. 
A third operation of heating and blowing still further enlarges 
the size of the glass, and reduces its substance. The side op- 
posite to the tube is then flattened by pressure against a plane 

Fig. 10. 




surface ; a small portion of melted glass is collected on the end 
of a punt, and is applied to the centre of this flattened side, 
forming an union with it exactly opposite to the hollow tube, 



CHAP. V. 



CROWN GLASS. 



147 



which is then removed by wetting the glass near to their point 
of union, leaving a circular hole in the glass about two inches 
in diameter. 

At this period the glass must be again held to one of the 
openings of the furnace until it has become sufficiently hot and 
ductile for the further alteration of its shape. The workman 
then dexterously twirls the punt in his hand, slowly at first, 
and then more and more quickly, when the glass yields to the 
centrifugal impulse ; its diameter becomes greater and greater ; 
the hole just mentioned expands proportionally ; and when in 
this continued progression the doubled portion opposite to the 
iron rod, and between the periphery of the glass and the ori- 
fice, is diminished to an annulus or ring only a few inches 
wide, this in an unaccountable manner instantly flies com- 
pletely open, and the glass is converted into a plane disc of 
fifty to sixty inches diameter, having an uniform thickness 
throughout the entire plate, with the exception of the spot 
where it is attached to the iron rod, and where there is a knot 

Fig. 11. 




or lump which is called a bulVs eye. Twelve of these plates 
make up what is called a crate or side of glass. 

The effect of this operation upon persons who witness it for 
the first time is both pleasing and surprising in a high degree. 
The force wherewith the glass flies open at the close of the 
process would be sufficient, if its brittleness were not removed 
by heat, to break it into innumerable fragments. 

The plate, when thus finished, is detached from the iron rod 
by the usual method, and placed resting on its edge in the an- 



148 GLASS MANUFACTURE. CHAP. V. 

nealing oven. Some considerable care is necessary for regula- 
ting the temperature at this stage ; for if the heat be too great, 
the softened glass will bend, and for that reason will be lessen- 
ed in value, while, if the oven be not sufficiently hot, the plates 
are very likely to crack ; and if even this disaster should not 
happen, the glass will prove of inferior quality, and so brittle, 
that the glazier will be unable to cut it with any degree of cer- 
tainty in the wished-for direction. 

Crown glass is sold, according to its quality, under four dif- 
ferent denominations — firsts, seconds, thirds, and fourths — at 
considerable difference of price ; that of the fourth quality not 
yielding to the manufacturer nearly one half of the price of 
the first. These variations arise principally from the want of 
sufficient care on the part of the attendants, in maintaining the 
necessary degree of heat in the furnace. If this is once suffer- 
ed to fall, the property of glass in being a very imperfect con- 
ductor of heat renders it difficult again to raise it to the former 
degree. In the operations of a large glass-house, it does not 
often happen that beyond one third of the quantity made is of 
the first quality ; seconds and thirds compose the largest propor- 
tion of the produce; and it seldom occurs that the quality 
sinks below the latter of these two denominations. 

Large plates of crown glass, such as are required for glazing 
engraved prints, used formerly to be imported from Germany. 
This country has, however, for a long time, been not only in- 
dependent in this respect of all foreign manufacturers, but 
similar plates of English make are exported to a considerable 
extent. 

Broad glass is a common coarse description of window glass, 
made of inferior ingredients, and by a somewhat different pro- 
cess of manufacture than that last described. The material 
principally employed for the purpose is soap-boiler's waste. 
This compound is a pasty mass, consisting of the insoluble mat- 
ter of the kelp or barilla, and of the lime which has been used 
to render the alkali caustic, together with a quantity of salt 
and water. This substance is united with kelp and sand, and 
the mixture is dried and fritted. The proportions wherein the 
ingredients are used necessarily vary according to the quality 
of the principal constituents, and the manufacturer must be 
guided by practical knowledge in apportioning the quantities. 

A very usual mixture is six measures of soap-boiler's waste, 
three of kelp, and three to four measures of sand. The quality 
of the last of these ingredients is of greater moment to the 
manufacturer than would seem to be generally imagined. 
Coarse sand is known to require a greater quantity of alkali 
for its fusion than that which is fine ; and as, notwithstanding 



CHAP. \\ BROAD GLASS. 149 

this, the glass when made does not contain the alkali in a 
larger proportion, it follows, that the difference has been dissi- 
pated and lost during the process. The carbonaceous matter, 
which would injure the color of the glass, is principally burned 
out, and the carbonic acid gas separated during the fritting ; 
after the completion of which, the mass, still red-hot, is re- 
moved with iron shovels to the melting furnace, the crucibles 
are entirely filled, and after twelve or sixteen hours' exposure 
to the proper degree of heat, the whole is perfectly vitrified. 

The formation of this glass into sheets is thus performed : — 
The necessary quantity being collected upon the end of the 
iron tube, as already described, is expanded by the workman's 
breath into a globular, or rather into an elliptical shape, of about 
twelve inches diameter, and of the requisite thickness. This 
done, the glass is carried to the mouth of the oven ; and the end 
of the tube through which the workman has blown being 
closed, the further expansion by heat of the confined air causes 
the glass to burst in its weakest part. While still hot and duc- 
tile, it is then opened by a pair of shears through its entire 
length into a flat plate, which is then conveyed to the anneal- 
ing oven. 

More than one half of the entire manufacture of glass in 
Great Britain is composed of common green bottle glass. The 
quantity of this material upon which duty has been levied, on 
an average of the last six years, exceeds 11,000 tons annually. 
However considerable this amount may appear, it is not greater 
than the annual average manufacture of a similar period com- 
mencing in the year 1790, — a fact which may be thought ex- 
traordinary, when it is considered that during the intervening 
years our population has been importantly augmented ; that the 
comforts, and even the luxuries of life, have been brought with- 
in the reach of a much larger proportion of our fellow-country- 
men ; and that our colonial markets have, in the same time, 
been very considerably extended. The circumstance of the 
rate of duty having been doubled would hardly appear cause 
sufficient for thus arresting the progress of consumption in an 
article so generally required ; since this duty, at its highest 
rate, has never exceeded eight shillings per hundred weight. 
A more minute examination into the case leaves us, however, 
without any reason for doubting that to the increase of the 
rate of duty, and to it alone, is to be ascribed the check given 
to this branch of manufacture. In the year 1812, when the 
duty was 4s. 0^. per hundred weight, upwards of 13,000 tons 
of common bottle glass contributed towards the revenue. In 
the succeeding year, when an additional tax of 4s. OJd. was 
imposed, the consumption immediately fell to somewhere below 

N2 



150 GLASS MANUFACTURE. CHAP. V.| 

8000 tons. From this extreme depression it has since gradu- 
ally risen, through the increasing numhers and improved con-l 
dition of the community, and aided by a diminution of price, 
independent of the duty ; but even now the manufacture has 
not reached within 2500 tons of the point which it had attain- 
ed in the year 1812; thus in a very striking manner verifying 
the remark so often made as to the variance between common 
and legislative arithmetic, and proving the pernicious tendency 
of taxes levied upon articles of domestic manufacture. It is to] 
be hoped that the improvement of the national revenue conse- 
quent upon the progressive state of our manufacturing inte- 
rests, and the constantly ameliorating circumstances of many 
classes of the community, will enable the government to carry 
speedily into effect a measure already announced for abolishing 
entirely the duties upon glass of home fabric, when this branch 
of the manufacture will assuredly receive an impulse that will 
carry it far beyond the highest point to which it has ever yet 
attained. 

The composition of bottle glass is as little uniform as that of 
any other description of the material ; varying greatly in differ- 
ent parts of the kingdom, and indeed in almost every individ- 
ual manufactory. It is usually made of sand, lime, and some- 
times clay, any kind of alkali or alkaline ashes which may hap- 
pen to offer the greatest inducement in point of price, and some- 
times the vitreous slag produced from the fusion of iron ore. 
Soap-makers' waste is frequently used in the proportion of three 
measures to one measure of sand. 

The rate of duty upon this description of glass being only 
one eighth of that levied upon flint glass, tiie manufacturers 
are restricted to the use of the commonest kmd of sea or river 
sand, lest the revenue should suffer by the superior quality of 
this less burdened ware. This is unfortunate, since, for the 
reason already given, the employment of such coarse sand oc- 
casions the necessity for using a large portion of alkaline mat- 
ter, and, in that respect, increases the charges to the glass- 
blower. The impurity of the alkali, and the abundance of flux- 
ing materials of an earthy nature, joined to the very high degree 
of heat at which they are fused, occasion the glass to contain a 
very small proportion of real saline matter ; for which reason it 
is better qualified than flint glass to be employed as the recipi- 
ent of fluids which have any corrosive action. Chemical re- 
torts and subliming vessels, and carboys for containing aqua- 
fortis, should, for this reason, be always made with this common 
glass, which has this further advantage over flint glass — that it 
will bear a much stronger heat without being softened or un- 
dergoing any alteration of its shape. 



CHAP. V. BOTTLE GLASS. 151 

Bottle glass is a very hard and well vitrified substance, and 
is of less specific gravity than other descriptions. Loysel gives, 
as the composition usually employed in France for the produc- 
tion of this material, — 

Common white or yellow sand . . 100 parts. 

Coarse kelp 30 to 40 

Lixiviated earth of ashes 160 to 170 

Fresh wood or other ashes .... 30 to 40 
Yellow clay, or brick earth ... 80 to 100 
Broken glass ad libitum, usually 100 ; 
which composition does not produce any glass gall. 

At Newcastle upon Tyne, where the manufacture of bottle 
glass is much encouraged by the excessive cheapness of small 
coal, or slack, the manufacturers employ a mixture of lime and 
sea sand. This must be frequently wetted with sea water, 
which, on evaporating, deposits its salt ; the soda contained in 
this being the only alkali employed. When combined with 
silica, and exposed to a high degree of heat, lime appears to be 
endued with the property of decomposing common salt; its 
presence is, therefore, essential to the success of this operation. 
Articles made of bottle glass are fashioned by the same pro- 
cess as those of flint glass, with the exception of wine and beer 
bottles, the containing parts of which are blown in metallic 
moulds, in order to keep them nearly of an uniform size. The 
green color of this glass is owing to the presence of a portion 
of iron in the sea sand, and, probably also, in the vegetable ashes 
of which it is composed. 

If, during the time when the workmen are employed in 
moulding and blowing bottles, the melted glass should — as in- 
deed it frequently will — become cooler than is desirable for the 
purpose, so that it is found necessary to replenish the fire, so 
much dust will be thus occasioned, owing to the description of 
coal employed, that the surface of the melted glass will be cov- 
ered with carbonaceous matter. The effect of this upon the 
contents of the crucible is very curious. The glass, which had 
before remained perfectly quiet, becomes suddenly so disturbed 
throughout as to present the appearance of violent ebullition, 
and the whole mass is immediately crowded with an infinite 
number of minute air-bubbles, which, so long as they are suffer- 
ed to remain, render the glass wholly unfit for use. 

The time that would be required for burning away this car- 
bonaceous deposit, and to restore the glass to its former working 
state, would be so considerable, that it would be highly incon- 
venient to wait for the production of this effect ; and it is there- 
fore fortunate that a simple remedy has been discovered, which 



152 GLASS MANUFACTURE. CHAP. V. 

immediately and perfectly restores every thing to its former 
state. 

Whenever the accident here mentioned occurs, the work- 
man has only to throw a small quantity of water into the cruci- 
ble, when the whole mass will be immediately stilled, and the 
bubbles will as instantly disappear, so that the workman may 
proceed without further delay. This curious effect has been 
referred to the decomposition by heat of the water, which, giv- 
ing up its oxygen to the coal-dust, converts it into carbonic acid 
gas ; in which form it is instantly driven off by the excessive 
heat of the furnace, and is dissipated in the atmosphere. 

In 1780, the celebrated M. Chaptal recommended M. Ducros, 
a manufacturer of bottle glass, to make trial of a new material 
for his purpose. This gentleman entered in consequence upon 
various experiments, which were, many of them, to a certain 
extent, successful. The substance thus recommended, and 
which formed the basis of these experiments, was decomposed, 
pulverulent, basaltic earth. This is found in great abundance 
in many parts of France, and is equally obtainable in the valleys 
of all basaltic countries. 

In the first trial made of this earth by M. Ducros, it was fused 
in a glass pot without admixture with any other substance ; and 
the result obtained was glass of an exceedingly deep yellow 
color, and lustrous. In subsequent experiments, various pro- 
portions of sand were used in conjunction with the basaltic 
earth. The mixture that was found to answer the purpose best 
was where equal parts of each ingredient were employed. This 
produced glass of an olive green color. 

There was for some time a considerable demand for bottles 
thus composed ; but owing to a difficulty which the manufac- 
turer experienced in procuring materials having the requisite 
uniformity in their constituent parts, the manufacture was, after 
a time, abandoned. 

M. Alliot has published the results of a course of experiments 
made by him with basaltic earth, with a view to the composi- 
tion of glass. Not being able to have recourse to the furnace 
of a glass-house, M. Alliot was obliged to content himself with 
the less intense heat of a potter's kiln, wherein the different 
mixtures which he employed were severally heated during 
eighteen hours. It is probable that the results which he has 
detailed would have proved more satisfactory, could recourse 
have been had to a more efficient mode of heating. The ex- 
periments were all conducted in crucibles. 

No. 1. was filled with the pure basaltic earth. This, in fusing, 
was converted into a black glass, which was opaque, and tol- 
erably well melted. 



5HAP. V. BOTTLE GLASS. 153 

o. 2. contained a mixture composed in equal parts of basalt, 
ashes, and white quartz in powder. This produced a coffee- 
colored glass, which was lustrous, and somewhat resembled 
porcelain in appearance. 

o. 3. was charged with half basalt and half common sand. 
The glass produced from this compound appeared, when in 
the mass, of a blue-black color; but when small thin portions 
were examined, these proved of a yellowish green. This 
glass was tolerably well melted. 

to. 4. consisted of one third each basaltic earth, sand, and re- 
fuse soda. The result was a transparent glass of a greenish 
yellow color, and of good quality ; it was very smooth and 
shining, well melted, and would have formed excellent bot- 
tles. 

^o. 5. consisted wholly of sand taken from the river Orb, in 
the immediate neighborhood of which there is found a con- 
siderable quantity of basaltic earth. The glass from this sand 
was well melted, and appeared to be every way adapted for 
the manufacture of very good and serviceable glass bottles. 

This basaltic earth is exceedingly well qualified both for fu- 
ion by itself, and for employment as a fluxing material where 
)ther substances are used. It is found, by analysis, to contain 
ibout 45 parts of silex, 16 of alumine, 20 of oxide of iron, 9 of 
ime, and from 2J to 4 parts of pure soda ; three of these sub- 
tances being very powerful fluxes. 

Some other minerals have been proposed, on account of the 
oda which they contain, as well qualified for making glass : 
uch, for instance, is klingstein, which contains nearly one 
welfth part of its weight of that alkali ; but as the other flux- 
ing materials present in basaltic earth are wanting in those 
other minerals, they prove far less fusible. 

Whenever basaltic earth is largely employed in the compo- 
sition of glass, it usually proves of a dark olive green color, 
varying sometimes to a very deep yellow ; and it does not ap- 
pear at all probable that this color could in any material degree 
be corrected. The glass produced is specifically lighter than 
any common green bottle glass ; and at the same time is con- 
siderably harder and tougher, so as to bear, without injury, 
blows which would infallibly break ordinary glass. The quan- 
tity of alkali which it contains is small — much smaller, in fact, 
than is required to bring glass of every other description to a 
workable state. For this reason basaltic glass is peculiarly well 
qualified for chemical purposes ; as vessels made with it will 
resist the destructive action of corrosive liquids. 
In addition to the experiments already detailed as having 



154 GLASS MANUFACTURE. CHAP. VI. 

been made by him with basaltic earth, M. Alliot made trial of 
various other combinations for the production of bottle glass. 
He succeeded with the two following : — 

The first was a mixture in equal parts of ashes and a volca- 
nic granite. This fused perfectly, and produced a very fine 
dark and lustrous glass, exceedingly well qualified for the com- 
position of bottles. The second was composed of 1 part ordi- 
nary soda, 12 parts ashes, and 6 parts common sand. The glass 
thus formed was of a yellowish black color, interspersed with 
veins of bluish white, which were opaque. 

When the duty shall be removed, and the manufacturer finds 
himself without restriction in regard to the materials which he 
may employ, we may expect to witness some considerable im- 
provements in this branch of the glass-maker's art. 



CHAP. VI. 

OF THE MANUFACTURE OF PLATE GLASS. 

Different Descriptions of Plate Glass.— Blown Plates limited in Size.— Cast 
Plate Works at Ravenhead. — Difficulties of the Process. — Materials.— Va- 
rious Compositions.— Borax.— Mixing Materials. — Flitting. —Furnaces 
and Crucibles at St. Gobain— Pots.— Cuvettes.— Regulation of Firing. — 
Casting Tables. — Arrangement of Foundery at Ravenhead. — Annealing 
Ovens.— Process of Casting Plates. — Annealing. — Squaring.— Grinding. — 
Economical Improvement. — Smoothing. — Emery Powder. — Comparative 
Value of Large and Small Plates.— Polishing.— Silvering. — Preparation of 
Amalgam.— Mode of its Application. — Blowing Plate Glass. — Punching. — 
Partial Cutting.— Transfer to Pontil.— Completion of Cutting.— Opening. 
— Sizes of Plates.— Effect of Sun's Rays in Discoloring Plate Glass. 

Two descriptions of plate glass are made : one by blowing 
and opening, in the manner of broad glass, as already described ; 
the other by casting the melted materials upon a plane metallic 
surface, somewhat in the manner pursued for making sheet 
lead. 

Plates of glass which are blown are necessarily limited in 
their size, although some of considerable dimensions are pro- 
duced in this way. When cast, the extent of the plates may 
be much greater ; and, indeed, is limited only by the very heavy 
expense attending the erection of machinery, and the prosecu- 
tion of the manufacture in its various parts. Different manu- 
factories have been established at various times in this kingdom 
for the production of plate glass by blowing, but these, one after 
another, have mostly been discontinued. The last establish- 
ment of this kind in London existed a very few years since in 
East Smithfield; but being a private establishment, and the 
proprietors finding it impossible to continue a successful compe- 



CHAP. VI. PLATE GLASS. 155 

tition with the powerful corporate body alluded to in the first 
chapter of this treatise, the works have been discontinued ; and 
the only place in England where plate glass of any great mag- 
nitude is now manufactured, is on the premises of the British 
3 late Glass Company in Ravenhead, in Lancashire, where 
)lates are cast which equal, in every respect, the produce of 
he French manufactory at St. Gobain. The office of this cor- 
poration is at the foot of Blackfriars Bridge, in London ; and 
lere plates of glass of the most perfect quality, and of all di- 
mensions up to the prodigious length of 160 inches, may at all 
times be procured. 

Great reluctance has always been evinced by the proprietors 
of plate glass works to permit their examination by visitors. 

rsons are, indeed, occasionally admitted to view the myste- 
ries : but, either by their habits and rank in life, such individ- 
uals are unqualified or unlikely to describe what they witness ; 
or the relaxation is made in their favor under a seal of confi- 
dence, which renders it impossible that they should impart the 
information they have acquired. The late Mr. Parkes appears 
to have been fortunate in this respect; and having obtained 
)ermission to visit the works at Ravenhead, was not restrained 
rom publishing a short, but interesting, account of the pro- 
cesses which he witnessed. From this source the following 
description is drawn, as far, at least, as relates to the buildings 
and arrangements particularly used at Ravenhead. 

More care in the choice of materials, and greater nicety in 
conducting the processes, are required for the preparation of 
}late glass than are needed in any other branch of the manu- 
facture. The materials employed are sand, soda, and lime, to 
which are added manganese and oxide of cobalt as decoloring 
substances. The sand must be of the finest and whitest kind : 
the grains should be sharp, and of a moderate size ; if very 
small, they are likely to clot together, and consequently will 
not mix intimately with the alkali ; and if the grains are large, 
they are on this account longer in being fused. The sand 
must be passed through a wire sieve of the proper closeness 
into water, and should be well agitated to separate all dirt and 
impurities. The alkali used is always soda : this is preferred 
to potash : as glass made with the former substance is thinner, 
and flows better while hot, and yet is equally durable when 
cold. The quality of flowing freely is of the very first import- 
ance in casting large plates, which, to be perfect, require to be 
without streak or bubble. Another advantage attending the use 
of soda is this ; — that the neutral salts of which it is the base, 
such as muriate and sulphate of soda, and which, in this in- 
stance, constitute the glass gall, are dissipated more readily by 



156 GLASS MANUFACTURE. CHAP. VI, 

the heat of the furnace, than are the salts of which potash is 
the hase. The soda must be used in a state of considerable pu- 
rity ; and is generally either that which is separated from the 
ashes of barilla, and other soda plants, by lixiviation, or is pro- 
duced by the decomposition of common salt. 

Lime acts in promoting the fusibility of the silex and alkali, 
fulfilling thus the same office as is performed by litharge in the 
manufacture of flint glass. From one fifteenth to one twenty- 
fourth part of the whole materials is the largest proportion that 
can properly be used of lime ; any greater quantity would im- 
pair both the color and solidity of the glass. 

Manganese would have the effect of giving a slight tinge of 
red ; but when mixed in a proper proportion with the blue of 
the cobalt, and both together are met by the natural slight yel- 
low of the other materials, each neutralizes the other, so that 
scarcely any definable tint remains. 

In addition to these ingredients, a considerable quantity of 
fragments of glass, or, as it is called, cullet, is used in combina- 
tion with the fresh materials. Of these fragments there is al- 
ways an abundant supply in the glass-house, produced from 
what is spilt in casting, and from the ends and edges that are 
cut off in shaping the plates. This broken glass, or cullet, is 
previously made friable, by throwing it, while hot, into cold 
water. 

It is considered that the addition of one pound of pure soda is 
sufficient for four pounds of sand. But it is not enough, in the 
preparation of glass for casting, to apply the alkali only in the 
proportion necessary to produce good glass ; much more than 
this must be used, in order to procure the requisite degree of 
fluidity. 

The composition given by Loysel as being used in the great 
works at St. Gobain is this : — 

White sand, 100 parts 

Carbonate of lime, 12 

Soda, 45 to 48 

Fragments of glass of like quality, .... 100 

Oxide of manganese, 0^ 

Parkes recommends the following proportions, as qualified to 
produce plates of glass of the best description : — 

Lynn sand, previously well washed and dried, . . 720 parts 
Alkaline salt, containing 40 per cent, of soda, . . 450 

Lime, slaked and sifted, 80 

Nitre, 25 

Cullet, or broken plate glass, 425 

noo 



CHAP. VI. PLATE GLASS. 157 

These quantities are required to produce one pot of metal, which 
will yield 1200 pounds of good plate glass. 

Another author states the following proportions as being 
found to produce very fine glass : — 

Fine white sand, 300 pounds 

Soda, 200 

Lime, 30 

Oxide of manganese, 32 ounces 

Oxide of cobalt, 3 

Fragments of glass, 300 pounds 

The well-known property of borax, as a powerful flux, has 
occasioned the suggestion that, by its means, glass made with 
potash might be caused to flow in fusion as freely as that where- 
in soda is employed. It has been asserted that small quantities 
of borax have always been used in the works at St. Gobain ; 
but the secrecy observed in regard to all the operations carried 
on in that establishment renders it impossible to say what de- 
gree of truth there is in the assertion. 

Great care is required in mixing the materials; mucli more, 
indeed, than is called for in regard to other kinds of glass. The 
sand, lime, soda, and manganese, being properly intermingled, 
are fritted in small furnaces, wherein the temperature is grad- 
ually raised to a full red, or even to a white, heat, at which 
point it is maintained, and the materials are carefully stirred 
until vapor is no longer given off, and no further change is un- 
dergone by the materials. This process of fritting lasts about 
six hours ; and when it is nearly completed, the remaining part 
of the ingredients, consisting of the cobalt and broken glass, are 
added. The latter, having already been perfectly vitrified, does 
not, consequently, require any lengthened exposure to the fire. 

The furnaces at St. Gobain, in which the perfect fusion and 
vitrification are accomplished, are eighteen feet long and fifteen 
wide. They contain two kinds of crucibles. The larger ones, 
wherein the glass is melted, are called pots, and are formed 
like inverted truncated cones ; the other crucibles, which are 
smaller, are called cuvettes : these last are kept empty in the 
furnaces, exposed to the full degree of its heat, that when the 
glass is ready for casting, and is transferred to them, they may 
not injuriously lower its temperature. The comparative size 
of these cuvettes varies according to the dimensions of the 
plates which it is intended to cast : when these are very large, 
the cuvette will contain one third of the charge of the pot ; but 
in other cases its capacity is not greater than a fourth, a fifth, 
or a sixth part, of the contents of the crucible. 

The method used for regulating the supply of fuel to the fur- 

O 



158 GLASS MANUFACTURE. CHAP. VI. 

nace in the great works of St. Gobain, is at once so rude and 
so absurd, that one would hesitate to believe in the correctness 
of the narration, if it did not rest upon good authority. It is 
said that two persons are employed, who, being disencumbered 
of all superfluous clothing, incessantly run round the furnace 
with a speed " equal to seven leagues in six hours." These 
men on their circuit take up each two small billets of wood, cut 
to a certain size, and heaped together ; these they deposit as 
they run, first one and then the other, in the openings of the 
furnace, which by such means is fed at regularly recurring in- 
tervals of time. Having continued this intellectual employ- 
ment, without ceasing, during six hours, the men then surren- 
der their " seven league boots" to others, whose heels and hands 
are similarly employed during an equal period of time ; after 
which they are in turn relieved by the first set of couriers. 

From the time of filling the pots, it requires nearly forty 
hours' exposure to strong heat, ere the materials are properly 
vitrified and in a state fit for casting. The processes of filling 
the pots, and of removing the glass gall, and the various ap- 
pearances that ensue in the refining, are precisely similar to 
what has already been described in a former chapter. 

When the glass is thoroughly refined, the cuvette — which 
must be perfectly clean, and, as already mentioned, of a tem- 
perature equal with that of the glass — is filled in the following 
manner: A copper ladle, ten to twelve inches in diameter, 
fixed to an iron handle seven feet long, is plunged into the glass 
pot, and brought up filled with metal glass, which is transfer- 
red to the cuvette ; the ladle, during this transference, is 
supported upon a strong iron rest, placed under its bottom, 
and held by two other workmen. This precaution is neces- 
sary to prevent the bending and giving way of the red-hot 
copper under the weight of fluid glass which it contains. When 
by successive ladings the cuvette is filled, it is suffered to re- 
main during some hours in the furnace, that the air-bubbles 
formed by this disturbance may have time to rise and disperse ; 
an effect which is ascertained to have ensued by the inspection 
of samples withdrawn from time to time for the purpose. 

Another essential part of the apparatus consists in flat tables 
whereon the plates of glass are cast. These tables have per- 
fectly smooth and level metallic surfaces, of suitable dimen- 
sions and solidity, supported by masonry. At St. Gobain, and 
formerly also at Ravenhead, these tables were made of copper ; 
the reason assigned for preferring this metal being, that it does 
not discolor the hot melted glass, while the use of iron was 
thought to be accompanied by this disadvantage. These copper 
tables were very costly, both from the nature of their material, 
and the labor bestowed in grinding and polishing their surfaces ; 



CHAP. VI. PLATE GLASS. 159 

and as the sudden access of heat that accompanied the pouring 
over them of such a torrent of melted glass occasioned the 
metal frequently to crack, the tables were by such an accident 
rendered useless. The British Plate Glass Company having 
experienced several disasters of this nature, its directors deter- 
mined upon making trial of iron ; and they accordingly pro- 
cured a plate to be cast, fifteen feet long, nine feet wide, and 
six inches thick, which has fully answered the intended purpose 
— having, during several years of constant use, stood uninjured 
through all the sudden and violent alternations of temperature 
to which it has been exposed. This table is so massive, weigh- 
ing nearly fourteen tons, that it became necessary to construct 
a carriage purposely for its conveyance from the iron foundery 
to the glass-house. It is supported on casters, for the conveni- 
ence of readily removing it towards the mouths of the different 
annealing ovens. 

The foundery at Ravenhead wherein this table is used is said 
to be the largest room under one roof that has ever yet been 
erected in this kingdom ; it is 339 feet long, 155 wide, and pro- 
portionately lofty. Westminster Hall, to which the superiority 
in this respect is so commonly ascribed, is smaller — its length 
being 300, and its breadth only 100 feet. The melting fur- 
naces, which are ranged down the centre, occupy about one 
third of the whole area of this apartment. The annealing ovens 
are placed in two rows, one on each side of the foundery, and 
occupy the greatest proportion of the side walls. Each of these 
ovens is sixteen feet wide and forty feet deep, Their floors 
being level with the surface of the casting table, the plates of 
glass may be deposited in them immediately after they are cast, 
with little difficulty and without delay. 

When the melted glass in the cuvette is found to be in the 
exact state that experience has pointed out as being most fa- 
vorable for its flowing readily and equably, this vessel is with- 
drawn from the furnace by means of a crane, and is placed 
upon a low carriage, in order to its removal to the casting table, 
which, as it is previously placed contiguous to the annealing 
oven that is to be filled, may therefore be at a considerable dis- 
tance from the melting furnace. Measures are then taken for 
cleaning the exterior of the crucible, and for carefully removing 
with a broad copper sabre any scum that may have formed upon 
the surface of the glass, as the mixture of any of these foreign 
matters would infallibly spoil the beauty of the plate. These 
done, the cuvette is wound up to a sufficient height by a crane ; 
air 1 then, by means of another simple piece of mechanism, is 
swung over the upper end of the casting table ; and being 
thrown into an inclined position, a torrent of melted glass is 



160 



GLASS MANUFACTURE. 



CHAP. VI. 



suddenly poured out on the surface of the table, which must 
previously have been heated, and wiped perfectly clean. 

Fig. 12. 




The glass is prevented from running off the sides of the table 
by ribs of metal, one of which is placed along the whole length 
of each side, their depth being the exact measure which it is 
desired to give to the thickness of the glass. A similar rib, at- 
tached to a cross piece, is temporarily held, during the casting, 
at the lower end of the table. When the whole contents of 
the crucible have been delivered, a large hollow copper cylin- 
der, which has been made perfectly true and smooth in a turn- 
ing-lathe, and which extends entirely across the table, resting 
on the side ribs, is set in motion ; and the glass, during its pro- 
gress, is spread out into a sheet of uniform breadth and thick- 
ness. Its length depends upon the quantity of melted glass 
contained in the cuvette : should this be more than is needed 
for the formation of a plate having the full dimensions of the 
table, the metal rib is removed from its lower part, and the sur- 
plus glass is received in a vessel of water placed under the ex- 
treme end for the purpose. 

Mr. Parkes, in speaking of this operation, remarks — " The 
spectacle of such a vast body of melted glass poured at once 
from an immense crucible, on a metallic table of great magni- 
tude, is truly grand ; and the variety of colors which the plate 
exhibits immediately after the roller has passed over it, renders 
this an operation far more splendid and interesting than can 
possibly be described." 



CHAP. VI* PLATE GLASS. 161 

At least twenty workmen are busily employed during this 
process of casting. From the time that the cuvette is removed 
from the furnace, to the completion of the casting by the hard- 
ening of the glass, the apartment must be kept as free as pos- 
sible from disturbance ; even the opening and shutting of a door 
might, by setting the air in motion, disturb the surface of the 
glass, and thus impair the value of the plate. So soon as it is 
completely set, the plate is carefully inspected ; and should any 
flaws or bubbles appear upon any part of its surface, it is im- 
mediately divided by cutting through them. 

When the plate of glass thus formed has been sufficiently 
fixed by cooling, it is slipped from the table gradually and care- 
fully into one of the annealing ovens, where it remains in a 
horizontal position ; its treatment differing in this respect from 
that pursued with crown and broad glass, which stand on edge 
during the annealing process. As each oven in this manner 
becomes filled, it is closed up by an iron door, the crevices of 
which are carefully stopped with mortar or clay, to prevent 
any access of external air to the oven ; and thus to provide as 
far as possible for the gradual cooling of the plates, the neces- 
sity for which has already been sufficiently explained. When 
the glass has remained during about fifteen days in these ovens, 
they are opened, and the contents withdrawn. 

The plates have then to undergo all the operations of squa- 
ring, grinding, polishing, and silvering, in order to fit them for 
sale. 

The first process — that of squaring and smoothing the edges 
— is performed by passing a rough diamond along the surface 
of the glass, guided by a square rule ; the diamond cuts to a 
certain depth into the substance, when, by gently striking the 
glass with a small hammer underneath the part which is cut, 
the piece comes away ; and the roughnesses of the edge thus 
left are removed by pincers. The plate is then taken to the 
grinding apartment. 

The next step is to embed each of the plates upon a table or 
frame adjusted horizontally, and made of either freestone or 
wood, cementing the glass securely thereto by plaster of Paris. 
One plate being then reversed and suspended over another, the 
material employed in grinding their surfaces is introduced be- 
tween the two, and they are made to rub steadily and evenly 
upon each other by means of machinery set in motion by a 
steam-engine. It was formerly usual to employ river sand and 
water, for the purpose of abrading the surfaces; a circumstance 
which entailed considerable waste and loss upon the manufac- 
turers. The glass which was ground off, and which usually 
amounts to one half the weight of the plates as they are cast, 

02 



162 GLASS MANUFACTURE. CHAP. VI. 

being thus mixed with a material which contained a portion of 
iron, was sold at a low rate for making bottle glass, or for 
scouring pewter. Mr. Parkes has calculated that the loss of 
glass by this means to one establishment — that which was car- 
ried on in East Smithfield — amounted to two tons weekly ; and 
that the expenditure of sand in the same period was at least 
sixteen to twenty tons. 

A method has, however, been devised for saving the whole 
of this glass, so as to render it available for the manufacture 
of the better descriptions. This plan consists in substituting, 
for the river sand before mentioned, ground flints, which con- 
tain no portion of iron. A further great advantage attending 
this method is, that one ton of ground flints is equally effective 
with five tons of sand, and that the operation is completed in a 
shorter time than formerly. 

When, one side of each plate has been sufficiently ground, it 
is loosened from the frame, and turned over, so as to present 
the other surface to be ground in the same manner. Some de- 
gree of pressure is employed, by loading the upper plate with 
weights as the grinding of each side approaches to completion. 
The process thus described used formerly to last during three 
entire days, but this time is now much abridged. The greatest 
attention is required, in order to finish with the surfaces per- 
fectly level and parallel, for which end a rule and plumb line 
are employed. 

By means of this grinding, the plates will have been made 
level, and all inequalities in the surface will have been re- 
moved ; but they are too rough to receive a polish : to fit them 
for this, they must again be ground with emery powder of in- 
creasing degrees of fineness. The preparation and sorting of 
this powder are effected in the following simple and ingenious 
manner : — 

A considerable quantity of emery is put into a vessel con- 
taining water, and is stirred about violently until the whole is 
mechanically mixed with the water. Emery is absolutely in- 
soluble by such means ; and if the mixture were left at rest 
during a sufficient time, the whole would subside in layers ; 
the coarsest and heaviest particles sinking first, and so on suc- 
cessively, until the very finest particles would range themselves 
as the upper stratum. Previously to this, however, and while 
these finest grains are still suspended in the water, it is poured 
off into a separate vessel, and the emery is there allowed to 
settle. A fresh supply of water is poured into the first vessel, 
the contents of which are again violently agitated, and allowed 
partially to subside as before. A shorter interval is allowed for 
this than in the first case ; and then the liquor is poured off into 



CHAP. VI. 



PLATE GLASS. 



163 



a third vessel, by which means emery of the second degree of 
fineness is separated. This operation is repeated, in order to 
obtain powders having four different degrees of fineness : the 
deposits are then separately dried upon a stove to a consistence 
proper for making them up into small balls, in which form they 
are delivered to the workman. 

In this further rubbing together, or, as it is called, smoothing 
of the glass plates, it must be understood that the coarsest 
emery is first used, and so on, substituting powders having in- 
creasing degrees of fineness as the work proceeds. 

This operation completed, the glass is perfectly even ; and 
although the surfaces appear opaque or deadened, they are so 
smooth that no scratchiness is at all perceptible. The plates 
are now again subjected to a rigid examination ; and should any 
flaws or defects be perceptible in them, which had before es- 
caped detection, they are cut up with a diamond into smaller 
plates, so that the blemishes are left at their edges ; regard be- 
ing had to economy in dividing the glass, so as to produce the 
smallest possible number of pieces. Attention to this circum- 
stance is of the greatest importance to the profitable working 
of the establishment, since the value of smaller plates bears no 
comparison with that of glasses having more considerable di- 
mensions. This may be seen at once in referring to the fol- 
lowing table, which has been calculated upon some of the pub- 
lished prices of the British Plate Glass Company. 





Dimensions. 


Surface in Square 
Inches. 


Price. 


Price per 
Sq. Inch. 








£ s. d. 


d. 


60 inches by 30 inches. 


1,800 


10 10 1 


1-400 


60 


- - - 40 - - 


2,400 


16 3 5 


1-617 


60 


- - - 50 - - 


3,000 


22 10 5 


1-800 


70 


- - - 50 - - 


3,500 


28 7 8 


1-946 


80 


- - - 50 - - 


4,000 


34 14 10 


2085 


100 


- - - 50 - - 


5,000 


48 9 8 


1-327 


100 


- - - 60 - - 


6,000 


63 15 1 


2-550 


100 


- - - 70 - - 


7,000 


80 8 2 


2-757 


100 


- - - 80 - - 


8,000 


98 4 10 


2-947 


132 


... 84 - - 


11,088 


200 8 


4-337 


160 


- - - 80 - - 


12,800 


246 15 4 


4-705 



The largest of the plates here mentioned is capable by reduc- 
tion of being converted into 7J plates having the dimensions of 
the smallest in the Table ; whereas the price of the former is 
23J times greater than that of each of the small plates, and 



164 GLASS MANUFACTURE. CHAP. VI. 

more than S\ times the aggregate value of those into which it 
would be divided. 

The reason for this progressional rate in the prices is suffi- 
ciently obvious. Could such a degree of perfection be attained 
in the different processes of manufacture, that a certainty ex- 
isted of producing plates of every requisite dimension, there 
would no longer be any pretence lor thus enhancing the prices 
of the larger pieces ; and plates might be sold indiscriminately 
at so much per superficial foot in the manner usual with linen 
or woollen fabrics, making perhaps some allowance for the 
greater expensiveness of machinery required for large than for 
small operations. But such a degree of certainty is so far from 
accompanying the labors of the glass-founder, that it is but very 
rarely he is enabled to finish and produce for sale any plates of 
extra dimensions ; while it most frequently happens that the 
presence of numerous flaws and bubbles compels the division 
and subdivision of the glass into portions bearing, for the very 
reason of their abundance, only a small relative value. 

It is represented as being an interesting sight to witness the 
grinding and smoothing of a great number of plates of large 
dimensions, which by means of machinery are thus made to 
move with great velocity, and in all directions. 

The next process is that of polishing. For this purpose a 
substance is used, known in commerce and the arts as colcothar 
or crocus martis. This is the brown red oxide of iron, which 
remains in the retorts after the distillation of the acid from 
sulphate of iron. 

The instrument used in polishing is a piece of wood covered 
with many folds of woollen cloth, each fold having between it 
some carded wool, so that the whole forms a tolerably hard but 
elastic cushion ; and this is furnished with a handle for the con- 
venience of the workman. 

The plate is embedded in plaster upon the table in the man- 
ner already described, and the polishing instrument being wet- 
ted by means of a brush, and covered with colcothar, the work- 
man commences his operation by rubbing the cushion backward 
and forward over the surface of the plate ; not, indeed, attempt- 
ing to polish the entire surface at the same time, but operating 
upon separate portions, beginning at each corner, and proceed- 
ing regularly towards the centre, so as to leave no part unvis- 
ited by its due degree of attention and labor. 

Considerable dexterity and practical skill are needed, not 
only to produce a high polish upon the plate, but also to give 
this in an uniform degree over its whole surface ; and the 
finishing touches require, therefore, to be given with great care 
and judgment. 



CHAP, VI. PLATE GLASS. 165 

When one side is polished, the plate is turned on the table, 
as it has before been in grinding" and smoothing ; but as the 
white plaster would appear through the glass and hinder the 
workman from forming an accurate judgment upon his progress 
in this second operation, the previously polished side is provided 
with a coating of red coicothar. When the workman is satis- 
fied with the result of his labor upon this second surface, the 
plate is taken from the table, and being cleaned, is laid, each 
side in its turn, upon a dark blue or black cloth, which, as it 
admits only a moderate light, shows by inspection any parts 
which may be less elaborately polished than the rest : these 
must be retouched by a small polishing cushion, in the same 
manner as before. 

It would be a tedious operation, if every small fragment of 
glass, such pieces, for instance, as are used in swing frames on 
toilet-tables, must be polished separately. The edges of several 
of these pieces are therefore brought together for the purpose ; 
but as all these are not of one uniform thickness, it is necessary 
to remedy this inconvenience ; and, in order to bring their sur- 
faces to a perfect level, they are arranged, with the side to be 
>olished downwards, on a large smooth level plate ; plaster of 
aris is then poured upon their upper surfaces, which are thus 
mbedded together, and on being turned over, the whole num- 
ber of pieces is found to be so level, that the polishing may be 
Derformed as easily and as effectually as it could be with one 
ntire plate. 

When the polishing of the plates has been satisfactorily com- 
leted, they are washed with water, and are either removed to 
le ware-room for sale, or, in case of their being intended for 
nirrors, to the silvering apartment. 

The last process used in a plate-glass manufactory is that 
vhich is called silvering. This, in common with the greater 
art of the operation connected with this branch of the art, is 
imple, but requires practice and dexterous management for its 
roper performance. The application to the posterior surface 
f mirrors of some substance that will accurately reflect the 
ays of light falling upon them, is absolutely necessary to ren- 
er them useful. The substance which has been found to an- 
wer this purpose best is mercury ; which, as it cannot be ap- 
lied alone in its fluid state, is, by a partial amalgamation, pre- 
iously made to adhere to the surface, and afterwards to incor- 
orate itself with the substance of a very thin leaf of tinfoil. 
The operation is thus conducted : — A perfectly flat and 

Imooth slab of thick wood, or of stone, somewhat larger than 
.ny plate which it may be required to silver, must be inclosed 



166 GLASS MANUFACTURE. CHAP. VI. 

few inches deep round three of its sides. The bottom of this 
frame is provided with a channel to collect the surplus mer- 
cury, and to convey it to a vessel placed underneath. The slab 
is fixed on a pivot, so that one end may be raised and the other 
depressed at pleasure. 

When it is used, the slab must first be adjusted horizontally, 
and covered with gray paper stretched tightly over it. A sheet 
of very thin tinfoil, a little larger than the plate to be silvered, 
is then laid smooth upon the paper, and as much mercury is 
poured steadily upon it as will remain upon its flat surface, 
That end of the slab which is unprovided with a ledge is then 
covered with parchment, and the plate of glass is carefully slid- 
den into the frame, resting the while upon the parchment. 

The art of properly effecting this deposit of the glass upon 
the foil consists in holding it, during its sliding, in such a posi 
tion that it will dip into the mercury, carrying a portion of the 
metal before it, but without once touching the tin in its pas- 
sage. By this means any dust or oxide which may rest upon 
the mercury will be removed, and no air-bubbles will remain 
between the glass and the foil ; while, if the tin were touched 
however slightly, it would certainly be torn. 

When the entire surface of the glass plate has thus passed, 
it is allowed gently to drop on the tinfoil, and to squeeze out 
the superfluous mercury from between, and which is collectec 
in the channel already mentioned. The plate being then cov 
ered with a thick flannel, is loaded at regular intervals of space 
with considerable weights, and the end of the slab is a little 
raised, which assists the escape of the superabundant mercury. 
The whole remains in this situation during the entire day, the 
slope of the slab being gradually increased to facilitate the 
dropping of the mercury. At the end of this time, the plate 
is cautiously taken from the frame, carefully avoiding to touch 
the under side, then covered uniformly with a soft amalgam of 
tin and mercury. The plate is then placed in a wooden frame 
and left during several days until the amalgam is found to b 
so far hardened as to adhere with a great degree of firmness 
to the glass : in this state not even a slight scratch would suf- 
fice for its removal. The plate is then in a finished state, anc 
fit for being framed. 

The amalgam does not, however, acquire its greatest degree 
of hardness until some time has elapsed ; and globules of Mer 
cury will occasionally drop from mirrors for some time even 
after they have been framed. Portions of the amalgam are at 
times detached while in this state, by violent concussions of the 
air, such as a thunder storm, or the firing of artillery. No 
patching can ever be applied in such a case that will be sufh* 



CHAP. VI. PLATE GLASS. 167 

ciently perfect to escape detection ; but a white seam will in- 
variably be perceptible at the points of junction. 

Although the processes followed in blowing plate glass are, 
in most respects, similar to those used in fashioning broad glass, 
some difference is yet observed ; which, indeed, is occasioned 

much through the increased bulk and weight of the mass 
under operation, as on account of any real difference in the 
omposition of the fabrics ; only a very short account of the 
jrocess can therefore be required. 

The first instrument used is a hollow rod, agreeing in every 
mrticular, except its size, with that used for forming flint and 
;rown glass. This rod is full six feet in length, and two inches 
n diameter ; made smaller at the end to which the breath is 
ipplied, and widened at the extremity upon which the glass is 
gathered. It is necessary to take up a considerable weight of 
lass upon this tube ; and some management is required in 
>rder to effect this. When the workman has gathered all 
hat will adhere by turning the end continually round in the 
>ot, he then withdraws it from the furnace; and holding it 
>ver a bucket of water, sprinkles the glass on the end of the 
ube, turning it constantly round in his hand. When cooled in 
his manner, the glass adheres firmly to the tube, and is rendered 
y that means capable of sustaining a greater weight than it 
vould otherwise support. The tube is then dipped again into 
he pot, and the same process is repeated. 

Fig. 13. 




After the third dipping it will have gathered a mass of glass 
the shape of a pear, ten inches in diameter, and about 
iwelve inches long. This must again be cooled with sprink- 
ing as before ; and while the workman is at the same time 
)lowing into the tube, so as to give a hollow form to the glass, 
md to reduce it to the requisite thickness, the rod must be 
swung to and fro with an alternating motion, in order to length- 
en the shape of the material ; and this proceeding being several 
imes repeated, the glass assumes the form of a cylinder, the 
ower end of which is hemispherical. 

Fig. 14. 




168 



GLASS MANUFACTURE. 



CHAP. VI. 



The assistant is then placed three feet and a half from the 
ground, upon a stool, whereon are fixed two upright pieces of 
wood, with a cross piece of the same material, for the purpose 
of supporting the tube with the glass. These are held by the 
assistant in an oblique position, the end with the glass inclin- 
ing downwards, that the workman may be able, with an iron 
punching instrument and a mallet, to drive a hole through the 
centre of the hemispherical end of the cylinder. 

Fig. 15. 




The glass now is subjected to examination; and if found 
sufficiently free from imperfections, is held at the aperture of 
the furnace during seven or eight minutes to heat it again 
thoroughly. While thus held, the rod is supported in its hori- 
zontal position by a small iron trestle placed before the orifice 
of the furnace conveniently for that purpose. The glass being 
thus sufficiently softened by heat, the assistant is again mount- 
ed upon the stool ; and resting the tube upon the wooden cross- 
piece, twirls it round, while the workman insinuates a pair of 
large broad shears which are pointed at the end, into the hole 

Fig. 16. 




previously punched. This is gradually enlarged, until the 
glass, through its whole length, and except at the part where 
it is attached to the tube, has a cylindrical form. 

Fig. 17. 




The tube is then again rested on the trestle, and the glass is 
reheated at the furnace, when the shears are used to cut the cyl- 
inder through half its length, beginning at the open end, and 
proceeding towards the point where it is attached to the tube. 

Fig. 18. 




CHAP. VI. PtiATE glass. 169 

The next proceeding is to take a pontil, an instrument al- 
ready described as being a solid rod of iron of smaller diameter 
than the tube, from which last the.glass is now to be transferred 
to the pontil. This differs from the instrument used for the 
like purpose in making flint glass, by having an iron cross- 
piece, twelve inches in length, placed across its extreme end, 
and forming with it the letter T. The pontil being thoroughly 
heated at the end, a quantity of melted glass is gathered from 
the pot upon the cross-piece, which being presented to the diam- 
eter of the cylinder, the two cohere speedily and firmly to- 
gether : the hollow tube is then disconnected from the glass in 
the manner already described. 

Fig. 19. 




The pontil with the cylinder is now rested on the trestle, 
and presented to the furnace, that the end which has hitherto 
been attached to the tube may in turn be heated and subjected 
to the same processes as have just been effected with the other 
end : the extremity is opened by introducing the shears so as 
to complete the cylinder (fig. 20.); and then after a fresh 

Fig. 20. 




heating the workman cuts through the remaining half of the 
length of the cylinder in a line with and joining to the cut 
already mentioned, so that the cylinder is divided on one of 
its sides through its entire length. 

Fig. 21. 




The glass is then placed with the cut side upwards upon an 
iron shovel ; it is separated from the pontil, and immediately 
removed to the hottest part of the annealing oven, where it 
gradually becomes again heated to redness. Advantage is 
then taken of the softened state of the cylinder to open it, by 
the help of an appropriate iron instrument, lifting up and turn- 
ing back the cut edges of the glass, until the whole is flattened 
upon the hearth of the annealing oven. A small iron rake is 
then employed to push the plate along the floor to the end of 

P 



170 GLASS MANUFACTURE. CHAP. VI. 

the oven ; and when this has been filled through a succession 
of operations such as are here described, the door is stopped 

Fig. 22. 




and cemented. All further processes are in every respect the 
same as are followed with plates that have been cast. 

The great size and weight of the glass render these opera- 
tions exceedingly laborious, so that a man and his assistant can 
hardly do more than make one plate in an hour, nor can they 
continue their labor longer than six hours, resting during an 
equal space before they resume their toil. 

Plates which are blown cannot properly be made above forty- 
five, or at most fifty, inches in length, and with a proportionate 
breadth. They have sometimes been made larger, but are 
then too thin to admit of their properly bearing the processes 
of grinding and polishing, and are besides liable to warp, which 
of course destroys their value when employed as mirrors. 

It was long since observed, that by exposing plate glass to 
the solar rays, it is made to acquire a violet or purple tinge, 
and this so rapidly, that the alteration is clearly discernible at 
the end of one or two years. Some plates, originally colorless, 
which had thus become tinged, having been brought under the 
notice of Mr. Faraday, he was induced to experiment upon the 
subject. For this purpose, he procured three different pieces 
of plate glass, which were tinged so slightly as to appear alto- 
gether colorless, unless when viewed through their edges. 
Each of these pieces was broken into two portions, one of 
which was wrapped in paper, and set aside in a dark place ; 
while the portion from which it had been separated was ex- 
posed to the air and the' light of the sun. This exposure was 
commenced in the month of January ; and in the following Sep- 
tember a comparative examination was made. The pieces 
from which the light had been excluded exhibited no sign of 
change, while those which had been exposed had, in this short 
space of eight months, acquired so considerable a degree of 
color as would, under other circumstances, have created a 
doubt regarding their original identity. 



CHAP. VII. ARTIFICIAL GEMS. 171 

CHAPTER VII. 

ON THE COMPOSITION OF ARTIFICIAL GEMS. 

Great interest formerly attached to this subject.— Different Compositions 
for Artificial Gems. — Mode of Preparation. — Rock Crystal formerly em- 
ployed. — Not superior to Sand. — Diamond Pastes. — Selection of various 
Pastes for Imitating different Gems. — Reasons for such selection. 

A very considerable portion of every treatise on glass-ma- 
king, which was in existence a century ago, and which com- 
prises nearly the whole of what has ever been published on the 
subject, was devoted to the art of composing factitious gems. 
A great deal of mystery would seem to have been affected 
upon this subject on the part of the manufacturers, each one of 
whom was, or pretended to be, possessed of some secret recipe, 
which he thought superior to all others for the composition of 
these ornaments. 

A corresponding anxiety to acquire a knowledge of these 
mysteries being evinced on the part of the public, the authors 
above alluded to, so far acquiesced in this feeling as to load 
their writings with one receipt after another, in almost endless 
succession, and in following which the artist was assured, that 
he might successfully rival nature in the production of these 
much-admired objects. 

The greater part of the compositions thus recommended, if 
indeed they were ever used, has long since passed into neg- 
lect ; and it will not be necessary, in the present day, to insert 
more than a very few directions on the subject, which are given 
upon the authority of M. Fontanieu, as being well qualified, 
with the addition of various coloring matters, for counterfeiting 
precious stones. 

No. 1. is composed of 20 parts of litharge, 12 of silex, 4 of 
nitre, 4 of borax, and 2 parts of white arsenic. These ingre- 
dients should be fritted together in a crucible, and afterwards 
melted, in which state the whole must be poured suddenly into 
cold water. Any portion of lead which may have been revived 
in the metallic state will then be apparent and must be separa- 
ted. The glass may then be remelted for use. 

No. 2. For this composition, mix together 20 parts of ceruse, 
8 of silex in powder, 4 of carbonate of potash, and 2 of borax. 
When these are perfectly met.ted, the whole should be poured 
into water, and then remelted in a clean crucible, in the same 
manner as No. 1. 

No. 3. consists of 16 parts of minium, 8 of rock crystal in 
powder, 4 of nitre, and 4 of carbonate of potash. These ingre- 



172 GLASS MANUFACTURE. CHAP. VII. 

dients must be melted and remelted in the manner already de- 
scribed as necessary with the preceding mixtures. 

No. 4 differs essentially from the three foregoing combina- 
tions in being without any portion of lead. It is made with 24 
parts of borax, 8 parts of rock crystal, and 8 of carbonate of 
potash. The rock crystal, previous to its use for this purpose, 
must be reduced to a state of great purity, by fusing it with an 
excess of alkali, and then precipitating it by an excess of acid, 
in the form of an impalpable powder. 

No. 5. The processes necessary for the production of this 
species of glass are much more complex than the preceding. In 
the first place, 3 parts of alkali are to be fritted with 1 part of 
rock crystal, which mixture must then be dissolved in water 
and saturated with dilute nitric acid. The silex which is pre- 
cipitated by this means must then be edulcorated and dried, 
when it will appear in the form of a very fine impalpable pow- 
der. Two parts of this must be melted in a crucible with 3 
parts, by weight, of the best ceruse, and the glass which re- 
sults must be poured into water. Break this down and remelt 
it with one twelfth of its weight of borax, and pour it again into 
water. If this last product is once more melted with one twelfth 
of its weight of nitre, the result will be a very fine hard glass, 
having an extremely beautiful lustre. 

The length of time required for fusing hard glasses or pastes 
is at the least twenty-four hours. The process herein directed, 
of pouring the melted glass into water, and then remelting, is 
found to be of considerable use in thoroughly and intimately 
mixing the ingredients together. 

Of the foregoing compositions, No. I. will be found extreme- 
ly fusible, on account of its considerable proportion of fluxing 
materials. It calls for the employment of the very best descrip- 
tion of crucibles, in order to withstand, for the requisite time, 
the corroding effects of the mixture. If any kind of glass into 
the composition of which lead has not entered, is applied to and 
melted on the interior surface of the crucible, so as to line it 
with a perfect glaze previous to use, the evil just mentioned 
will be materially remedied. 

In order to make a perfect glass, which at the same time 
shall be sufficiently workable, 2 parts of silex require from 3 to 
4 parts, by weight, of oxide of lead ; but a somewhat smaller 
quantity of the latter may be used, if the deficiency is made up 
by the addition of some other fluxing material : the glass in 
this case will prove both hard and brilliant ; and, when proper- 
ly set, will exhibit a much nearer imitation of the diamond than 
most other vitreous compositions. 

It was formerly imagined by artists who wrought these arti- 



CHAP. VII. ARTIFICIAL GEMS. 

ficial gems, that if the glass employed by them had for its basis 
rock crystal, rather than sand, flint, or any other mineral of the 
like character, the result was a much harder glass than ordi- 
nary. This idea is, however, wholly without foundation ; for 
when the crystal has once been fused through the admixture 
of any kind of flux, the hardness of the mineral will be irrecov- 
erably lost, as this quality depends altogether upon its natural 
aggregation, which, in such case, is necessarily destroyed. 

Rock crystal is, perhaps, somewhat purer than most other 
siliceous substances, some of which contain minute traces of 
iron, and which may possibly impair the beauty of some colors 
which are imparted to glass. The same means as are used to 
render flint friable, are employed for that purpose with rock 
crystal: this should on no account be ground in metallic 
vessels. 

Some artists have succeeded, to a certain extent, in produ- 
cing a very fine, hard, brilliant, and colorless glass paste, in im- 
itation of the diamond, and have even given to this a very con- 
siderable play of light, or, as it is technically termed, water ; 
but it has not been found practicable to compound any vitreous 
substance which could for a moment deceive the eye of any 
person accustomed to witness the superior brilliancy of real 
gems. The best of these mock diamonds require, indeed, the 
aid of artifice in the mode of their setting, to render them in 
any great degree ornamental. M. Fontanien recommends his 
glass, No. 1, described in this Chapter, as being better quali- 
fied than any other for making artificial diamonds. To bring 
this glass to such a degree of brilliancy and clearness as will 
prove at all satisfactory, it must be retained in a state of per- 
fect fusion for a considerable space of time. 

Loysel recommends, for the same purpose, the employment 
of a "different composition, the result of which will be a glass, 
having the same specific gravity as the white oriental diamond, 
and for this reason better imitating that resplendent substance 
in its refractive and dispersive powers. His recipe is as fol- 
lows : — 

White sand purified by being washed first 
in muriatic acid, and afterwards in pure 
water, until all traces of the acid are 

removed 100 parts. 

Red oxide of lead (minium) 150 

Calcined potash 30 to 35 

Calcined borax 10 

Oxide of arsenic 1 

This composition is easily fusible at a moderate heat; but like 
that proposed by Fontanieu, requires to be kept in a melted 

P2 



GLASS MANUFACTURE. CHAP. VII. 

state for two or three days, to perfect the refining, and to cause 
the dissipation of the superabundant alkali. 

The same author has furnished the following receipts for the 
formation of pastes, qualified, upon the addition of appropriate 
coloring 1 materials, for the imitation of various gems. The re- 
marks already made as to the length of time required for the 
due preparation of the diamond paste equally apply to these 
compositions : — 

White sand, purified in the manner point- 
ed out in the preceding receipt, .... 100 parts. 

Red oxide of lead 200 

Calcined potash, and nitre, of each .... 20 to 25. 

The specific gravity of this glass, water being 1, will be 3.9 
to 4. 

White sand, prepared in the manner be- 
fore mentioned, 100 parts. 

Red oxide of lead, 300 

Calcined potash, 5 to 10 

Calcined borax, 200 to 300. 

The specific gravity of this compound will vary from 3*3 to 4. 

White sand, prepared as above, 100 parts. 

Red oxide of lead, 250 

Calcined potash, 15 to 20 

Calcined borax, 25 to 30. 

This will have a greater specific gravity varying from 4 to 
4.5. 

In making his selection between one or other of these pastes, 
the artist should be guided by their various specific gravities, 
choosing preferably that glass which is nearest in this respect 
to the particular gem which he is desirous of imitating ; and 
this, not with the view of providing himself with an additional 
means of deception, but because, the refractive and dispersive 
powers of different transparent bodies being determined by 
their comparative weights, the resemblance will, by such a 
selection, be rendered more perfect to the eye. To one simple 
test, that of their hardness, recourse can be had so easily, that 
every one may, with very little previous instruction, ascertain 
for himself the genuineness of any gem that is offered to his 
notice, without any apprehension of being deceived. 



CHAP. VIII. PHOSPHORIC GLASS. 175 

chap. vra. 

ON THE MANUFACTURE OF GLASS FROM CALCINED BONES. 

Preparation of Bones. — Their Vitrification. — Process known to Becher. — 
Concealed by him. — Curious Suggestion as to its Employment.— This 
Glass highly electric when newly made. 

Glass may be made from calcined bones by digesting them 
during two or three days with half their weight of sulphuric 
acid, evaporating to dryness, and washing the residue in many 
different waters, until all the soluble matter is exhausted. The 
production of this effect is known by the water having no 
longer a yellow tinge. 

The different waters thus used must then be brought to- 
gether and evaporated to afford a solid extract. To separate 
the sulphate of lime contained in this, the extract must be dis- 
solved in the least possible quantity of water, and filtered : the 
salt will then remain on the filter. This extract may be mixed 
with powdered charcoal, and distilled for the production of 
phosphorus ; but if, instead of this, it be placed in a large cru- 
cible, and the fire is urged, it will at first swell considerably, 
but ere long will again settle, and at that instant the glass is 
made. This is white, and of a milky color. 

These directions are taken from the System of Chemistry of 
M. Chaptal ; who tells us that before his time Becher was per- 
fectly well acquainted with the use to which bones could thus 
be applied, but that he concealed the process, on account of the 
abuse which, according to his apprehensions, might be made of 
it, and to which he plainly enough alludes in the words—" Ho- 
mo vitrum est, et in vitrum redigi potest ; sicut et omnia ani- 
malia." This author w T as, nevertheless, led to express his re- 
gret that the Scythians, who drank from disgusting skulls, were 
not acquainted with the art of converting them into so cleanly 
a substance as glass ; — and he also showed the possibility of 
forming a gallery of family effigies, moulded from glass, the 
produce of the identical bones of the originals, in which the 
likenesses might be preserved as truly as they now are by the 
limner. M. Chaptal adds, that a skeleton of nineteen pounds' 
weight may be made to yield five pounds of this phosphoric 
glass. 

Newly made glass of this description will emit very strong 
electric sparks, which will fly to the hand at the distance of two 
inches : but this property ceases after one or two days, however 
carefully the glass may be preserved from contact with the at- 
mosphere. The substance is in fact phosphoric acid which has 



176 GLASS MANUFACTURE. CHAP. IX. 

been deprived of its water, and which if not carefully preservec 
from the atmosphere it will again imbibe, becoming deliques 
cent. It has an acid taste, and is soluble in water. 



CHAP. IX. 



ON THE USE MADE OF THE BLOWPIPE, AND ON VARIOUS SMALJ 
MANUFACTURES OF GLASS. 

Thermometer Tubes. — Mode of giving to them an Elliptical Bore.— Blowpipe 
and Apparatus described. — Materials used. — Method of Working. — Seal 
ing Tubes.— Bending and Joining Tubes.— Bulbs.— Spun Glass.— Watch 
Glasses. — Lunette Glasses. — Glass Beads.— Manufactory at Murano.— 
Striped Tubes. — Mode of forming Beads.— Sorting them. — Numerous Kind; 
of Beads.— Mock Pearls.— Manner of their Invention and formation.— Dia 
Plates.— How formed.— Lettering and Figuring. 

A considerable number of articles are made of glass with 
the aid of a lamp and blowpipe. The principal of these articles, 
such as thermometers and barometers, are formed from tube 
which are made at the glass-houses, of different bores and sub- 
stances, by drawing out quickly, and while soft with heat, 
thick and short tube into one that is thin and long. 

The method of performing this process is, to gather the ne- 
cessary weight of glass upon the rod ; and this glass having 
been elongated and hollowed by the workman's breath in th 
usual manner, a punt is attached to the end of the cylinder op- 
posite to the rod. The workman then holding the rod and hi 
assistant the punt, each proceeds in a direction opposite to that 
taken by the other, by which means the tube is elongated in 
the necessary degree ; and being then made to rest upon billets 
of wood placed horizontally and parallel to each other at equal 
distances on the ground, it speedily cools, and may in that state 
be readily cut into convenient lengths. 

Fig. 23. 



Whatever may be the original form of this tube and of its 
perforation, it is found that the same form will be relatively 
continued throughout the entire length to which it is drawn 
out If its perforation be at first cylindrical, it will so continue, 



CHAP. IX. BLOWPIPE. 177 

whatever degree of length and minuteness it may be made to 
assume ; and an equal sameness will be found to accompany 
the prolongation, if any other form be originally given to the 
orifice. 

A method has been suggested by Mr. Wilson, of Glasgow, to 
render the mercury in a thermometer tube easily observable, 
without incurring the inconveniencies which attend a large 
bore. This method is founded on the property above mention- 
ed, and which is indeed common to all ductile substances* 
Mr. Wilson proposes to form the tubes with an elliptical per- 
foration, which when drawn out will form a mere slit, the flat 
side of which is to be turned towards the observer. It does not 
appear, however, that these tubes have come into any extensive 
use. 

This elliptical bore is caused by flattening, in the necessary 
degree, and before it is drawn out, the short thick tube already 
described ; restoring then its external cylindric form by coating 
it over with a further portion of melted glass, and rolling it on 
the iron slab, mentioned in page 137, in our description of the 
processes pursued in blowing flint glass. 

The apparatus usually employed by those who undertake this 
branch of glass-working is extremely simple. The table is 
substantially made, and has fixed at its bottom a small double- 
)last bellows, worked with a foot-board, that the artist may 
limself govern its action, and at the same time have both his 
lands at liberty for the other operations which he has to con- 
duct. A pipe, proceeding from the bellows, conducts the blast 
of air to the lamp, which is usually nothing but a bundle of 
coarse cotton thread, placed in a common tin vessel of a horse- 
shoe shape, the flame being fed with lumps of tallow heaped up 
and intermixed with the cotton. A small chimney is hung over 
the lamp, and at a short distance from the flame, to carry off 
the smoke, which otherwise would be inconvenient to the work- 
man. The blast pipe is so placed and directed that it throws 
off the jet of flame from the lamp in a direction contrary to that 
occupied by the workman, so that all annoyance from this source 
is equally avoided. 

Two or three very simple iron tools, such as files, forceps, 
scissors, &c, make up the rest of the glass- worker's apparatus ; 
vhile his materials are mostly confined to an assortment of 
ubes having various bores, and composed of different thick- 
nesses of glass. When employed in making toys or ornaments 
>f glass, tubes of various colors are provided by the workman : 
hese are easily procurable at any glass-house, a good stock of 

* For a beautiful scientific application of this principle, see Lardner's Me- 
chanics, Cab. Cyc. p. 9. art. (12.) 



178 GLASS MANUFACTURE. CHAP. U 

all kinds of tubing being generally kept by the makers. Th 
flame, when most strongly urged by the blowpipe, is about foi 
inches long, having its end of a blunt round form ; its colo 
in the part nearest to the wick, is of clear light blue, and b< 
yond this of a pale yellow, the blue portion having by far tl 
greatest heating power. 

In proceeding to work, care must be taken to remove i 
moisture from the tubes, both within and on the outside ; the 
must be heated gradually, to prevent their cracking ; and tl 
greater the thickness of the glass, the more necessity there is f< 
caution on this head. Glass is so imperfect a conductor of hea 
that where utensils made with it of any considerable thicknei 
have lire applied to them, it is difficult to prevent an unequal d 
gree of expansion, which induces that corresponding inequalit 
of pressure among the different parts under which some wi 
inevitably give way and fly asunder. It is for this reason tin 
glasses intended for use in chemical laboratories can hardly \ 
made too thin, or with too great attention to the equality of the 
substance, so that heat may be quickly and uniformly transmits 
through the mass. 

Glass tubes should be first heated by being held in the flan 
of the lamp, without employing the blast of air ; they shou 
next be brought to the yellow outer edge of the flame whe 
urged by the blowpipe ; and, lastly, the fusion must be complete 
through bringing the glass by slow degrees within the hotter 
part of the flame. 

The power of a blowpipe, such as is usually employed fc 
these purposes, is sufficient for bringing to a white heat a soli 
lump of glass large enough to form a bulb which will contai 
three fluid ounces ; a size much larger than can be required f< 
purposes to which the lamp is usually applied. 

It may be well to describe briefly one or two operations, sue 
as are usually effected by means of the lamp and blowpipe 
from which will be made apparent the great facility wherewit 
this seemingly refractory substance can be moulded, throug 
the agency of heat, according to the will of the workman. 

If it be wished to seal a tube hermetically, that is, to close 
effectually at the end by causing the intimate union of its pai 
tides, it will suffice that the part be held during a short tim 
in the flame, turning the tube round with the fingers so as t 
occasion an equal action upon every part : by this means th 
end will presently be so far softened, or partially fused, that th 
particles will fall in and run together; thus effectually closin 
the orifice, and producing the appearance of a small button a 
the extremity. This operation may be hastened, if, when 'th 
glass is rendered soft by heat, and before any fusion has ensuec 



CHAP. IX. BINDING TUBES. 179 

;he parts are brought into contact towards their common centre 
w means of a stout iron needle. In some cases, and particular- 
ly when the tube is of any considerable substance, the button 
thus formed on the end would be inconveniently large, and 
might besides either fly in cooling, or be accidentally broken. 
?his can be remedied by lessening, in the following manner, 
the quantity of glass whereof it is composed. 

The end being softened in the flame of the lamp, and another 
piece of tube of the same size having been equally acted upon, 
le two ends are to be brought together, and may, by a very 
ittle management, be firmly united. If then the tube which is 
to be sealed is softened a little higher up than the point of 
union, and the two tubes are pulled gently in opposite directions 
until they separate, that which is heated will be drawn out with 

diminished substance, and may be easily sealed in the part 
lat is required, the joined ends and a portion of the sealed tube 
emaining attached to the waste piece. 

In making some kinds of thermometers, and for various pur- 
Doses connected with experimental chemistry, it is often requir- 
d to bend tubes of glass : when these are of small bore, and 
leir substance is tolerably thick, it is only requisite to hold the 
ube in the weaker part of the flame, in order to soften it 
irough about one or two inches of its length, when it may be 
lowly and gently brought to the shape required. 

Something more than this is needed if the tube be wide and 
ts substance thin. In order to preserve in such case the particu- 
ar form of the bore, and to prevent its being much straightened, 
)r perhaps closed at the bend, as it most probably would be if no 
)recaution were taken against it, one end of the tube should be 
lermetically sealed ; and during the time the workman employs 
limself in bending it at the required part, he should also blow 
teadily but very gently into the open end. The pressure of 
lis breath employed in this manner, will keep the softened 
)art of the tube distended in the proper degree, so that it can- 
lot collapse during the bending, and the perforation will be 
naintained in its original form. The closed end of the tube 
nay be readily cut off by first scratching with a file and then 
reaking it suddenly ; an operation which, with a very little 
are, may be performed without risk of dividing the tube in any 
ther part of its length. 

Two tubes may be joined together with tolerable accuracy 
y heating their ends in the flame, and then bringing them 
ito contact ; turning them round in opposite directions with a 
crewing motion, in order to complete their junction. If it be 
esired to remove the thickened ring of glass which will thus 
Be produced, one end of the tube must then be previously seal- 



180 GLASS MANUFACTURE. CHAP. IX 

ed ; and when the union has been fully completed in the way 
described, and while the glass is yet soft, the workman mus 
blow into the open end, and gently pull the tube at the point of 
junction, until the ring disappears, and the whole tube become; 
equally cylindrical. 

In forming hollow bulbs at the end of tubes, such, for in 
stance, as are required in making thermometers, the following 
process must be used : — The end whereat the bulb is to be form 
ed must be sealed ; and in order to collect at this extremity th 
needful quantity of glass, it must be pressed while yet quite ho 
upon some hard surface, by which means that part is somewha 
shortened and consolidated into a lump. This must then h 
held in the most intense flame of the blowpipe until it is quit 
white hot ; being then removed, and the breath applied moder 
ately and steadily to the open end, and keeping the tube in th 
meanwhile with the heated end hanging downwards, th' 
lump will be enlarged into a spherical bulb, the diameter, an< 
consequently the substance, of which can be regulated accord 
ing to the pleasure of the workman. 

It has been already mentioned that glass may be spun int 
very long and minute threads, with great velocity, when th' 
mass from which it is drawn has been previously heated. Fo 
this operation the use of the blowpipe is required, and the man 
ner of its performance is very simple. 

The lump of glass being sufficiently softened by the flame 
another piece of glass is applied to it, when the two, cohering 
together, and being then drawn apart, are seen to be connectec 
by minute filaments. A fine thread being thus obtained, its enc 
is applied to a wheel or reel, and the heat of the glass being 
maintained, while the wheel is turned with considerable velo 
city, a thread may be drawn continuously out as long as the 
workman pleases, or until the store of glass is wholly expended 

The thread thus made is extremely flexible and delicately 
fine. Its firmness depends in a great measure upon the heat 
whereat the glass is maintained, and upon the velocity where 
with the wheel is turned : the greater these are, the firmer wil 
be the thread. 

Glass is only treated in this manner in order to afford a pleas- 
ing exemplification of some of its properties, or for purposes of 
ornament. When it is desired to produce colored threads, the 
-material employed should be embued with a very deep tint, as, 
when drawn out in such minute filaments, it would otherwise 
appear nearly colorless. 

The preparation of watch-glasses involves a series of simple 
but interesting processes. Only a part of these is performed at 



CHAP. IX. WATCH-GLASSES. 181 

the glass-house ; the remainder being the objects of a separate, 
and, when viewed with reference to its extent, by no means 
unimportant branch of trade and manufacture. 

All that is effected by the glass-blower is the production of 
regular hollow spheres, each being eight inches in diameter, 
and weighing twelve ounces. 

It is a circumstance, perhaps, not the least deserving of notice, 
in detailing the operations of the glass-house, that the men em- 
ployed to gather glass from the pots for this and similar pur- 
poses, upon the end of the hollow rods, attain through constant 
practice so much proficiency as to bring away with the great- 
est accuracy exactly the quantity that is needed for the forma- 
tion of the required object. To such a degree is this correct- 
ness carried, that, on weighing many dozens of spheres such as 
have just been described, not one has been found that varies 
half an ounce from the proper weight. 

The blowing of these hollow globes is performed with great 
celerity. Owing to the circumstance that the glass of which 
they are composed is exceedingly thin, so that their cooling, 
although rapid, is also effected with considerable regularity 
through their substance ; and because in the further progress 
towards their ultimate form they are again to be softened by 
heat, these globes are delivered to the watch-glass maker a3 
soon as they are blown, and without passing through the 
annealing oven. 

The first operation performed by the last-mentioned artist is 
to divide each sphere into the largest possible number of sec- 
tions of the requisite size ; it being manifest that any errors 
committed at this stage of the proceeding would, by wasting 
his material, place the manufacturer at a disadvantage. 

In proceeding to effect this division, the workman seats him- 
self; and taking the globe in his lap, with a piece of heated 
wire or tobacco-pipe, (which last is perhaps chosen preferably, 
because it longer retains a sufficient degree of heat,) he traces 
a line upon the globe, and quickly thereafter wetting the line 
thus traced, the glass will crack and divide along the line with 
the most' admirable precision. The sections thus obtained will 
necessarily have many angular irregularities : these are dexter- 
ously clipped away by means of scissors, 

The segments into which the individual pieces have now 
been cut, will be wanting in the requisite degree of convexity. 
Before this can be imparted to them, they must have their brit- 
tleness removed, and be considerably softened by heat. When 
this has been effected, taking an appropriate instrument in each 
hand, and using them much in the same manner as the dairy- 
maid employs her w T ooden spoons in raising a pat of butter, 

Q 



182 GLASS MANUFACTURE. CHAP. IX* 

the workman presses the edges of the glass regularly in to* 
wards the centre, which is by this means made to rise in a cor- 
responding proportion. The edges are then ground evenly off, 
and the watch-glass is ready for sale. 

Lunette glasses are differently made. These are not seg- 
ments of spheres, but have their edges abruptly raised, and 
their interior areas or faces flattened. In forming these lu- 
nettes, a much smaller quantity of glass is gathered from the 
pot than is required in blowing globes for ordinary watch- 
glasses. A hollow pear-shaped figure is then blown, having 
the larger end, which is farthest from the extremity of the rod, 
of the size required for a watch-glass, and the requisite flat- 
ness is occasioned by pressing this end, while soft, upon any 
smooth level surface. 

These glasses are necessarily much higher in price than 
those more commonly used for watches ; both because they are 
made to contain a greater weight of glass, and because, only 
one form being cut from each hollow pear-shaped figure, the 
labor expended in the manufacture is proportionally greater. 

A very considerable manufacture of glass for the formation 
of beads is carried on at a place called Murano, situated near 
the city of Venice. There is nothing peculiar in the composi- 
tion of the glass made use of for this purpose, nor in the meth- 
ods employed for its preparation ; and although the manufactu- 
rers affect great secrecy as to the coloring substances which 
they mix with the glass, it is not likely that they possess any 
real advantage over others in this respect, or that they have 
made any useful discovery of materials different from those 
commonly employed in coloring glass. 

When upon inspection the colored glass is found to be in a 
fit state for working, the necessary quantity is gathered in the 
usual manner upon the rod, and is blown into a hollow form. 
A second workman then provides himself with an appropriate 
instrument, with which he takes hold of the glass at the end 
which is farthest from the extremity of the rod, and the two 
men running thereupon expeditiously in exactly opposite direc- 
tions, the glass is drawn out into a pipe or tube, in the manner 
of those used for constructing thermometers, the thickness of 
which depends upon the distance by which the men separate 
themselves. Whatever this thickness may be, the perforation 
of the tube is preserved, and bears the same proportion rela- 
tively to the substance of the glass as was originally given to 
it by the blower. In these particulars the workmen of course 
govern themselves according to the size and description of the 
beads which are to be made. The glass-house at Murano is 



€HAP. IX. GLASS BEADS. 183 

provided with a kind of ,gallery 150 feet in length, and which 
much resembles a rope-walk, wherein the tubes are drawn out 
in the manner here described. 

Tubes striped witli different colors are made by gathering 
from two or more pots lumps of different colored glass, which 
are united by twisting them together before they are drawn 
out to the requisite length. 

As soon as they are sufficiently cool for the purpose, the 
tubes are divided into equal lengths, sorted according to their 
colors and sizes, packed in chests, and then dispatched to the 
city of Venice, within which the actual manufacture of the 
beads is conducted. 

When they arrive at the bead manufactory, the tubes are 
again very carefully inspected, and sorted according to their 
different diameters, preparatory to their being cut into pieces 
sufficiently small for making beads. 

For performing this latter operation, a sharp iron instrument 
is provided, shaped like a chisel, and securely fixed in a block 
of wood, Placing the glass tube upon the edge of this tool 
at the part to be separated; the workman then, with another 
sharp instrument in his hand, cuts, or rather chips, the pipe 
into pieces of the requisite size ; the skill of the man being 
shown by the uniformity of size preserved between the differ- 
ent fragments. 

» The minute pieces thus obtained are in the next process 
thrown into a bowl containing a mixture of sand and wood- 
ashes, in which they are continually stirred about until the 
perforations in the pieces are all filled by the sand and ashes. 
This provision is indispensable, in order to prevent the sides 
from felling together when softened by heat in the next opera- 
tion. 

A metallic vessel with a long handle is then provided, 
wherein the pieces of glass are placed, together with a further 
quantity of wood-ashes and sand ; and the whole being subject- 
ed to heat over a charcoal fire, are continually stirred with a 
hatchet-shaped spatula. By this simple means the beads ac- 
quire their globular form. 

When this has been imparted, and the beads are again cool, 
they are agitated in sieves, in order to separate the sand and 
ashes ; this done, they are transferred to other sieves of differ- 
ent degrees of fineness, in order to divide the beads according 
to their various sizes. Those of each size are then, after being 
strung by children upon separate threads, made up into bun- 
dles, and packed in casks for exportation. 

In this manner, not fewer than sixty different kinds of glass 
beads are prepared in vast quantities. The principal trade in 



184 GLASS MANUFACTURE. CHAP. IX, 

these is carried on with Spain and the coast of Africa ; but 
some portions find their way to nearly all parts of the world, 

Another and a more costly description of glass beads, made 
in imitation of pearls, has long been produced in France. Al- 
though the name of the inventor of these ornaments has been 
faithfully preserved, the period of their invention is not pre 
cisely known. Reaumur, on whose assertions the greatest re 
liance may generally be placed, states this to have occurred in 
1656. An anecdote related by Beckmann* of a cheat success 
fully played off upon a lady by a French nobleman, leads to the 
conclusion that thirty years later than the period here mention 
ed, these mock pearls were far from being generally introduced 
or even known. 

The manner of their invention was this : — M. Jaquin having 
observed that upon washing a small fish, .the Cyprinus albur- 
nus, or bleak, the water contained numerous fine particles, 
having the color of silver, and a pearly lustre, he suffered the 
water to stand for some time, and, collecting the sediment 
covered with it some beads made of plaster of Paris, the fa- 
vorable appearance of which induced him to manufacture more 
of the same kind for sale. These were at first eagerly adopt- 
ed ; but the ladies soon finding that when they were exposed 
to heat, the lustrous coating transferred itself from the beads 
to their skin, they were as quickly discarded. 

The next attempt of M. Jaquin was more successful. He 
procured some glass tubes of a quality easily fusible, and, by 
means of a blowpipe, converted these into numerous hollow 
globules. He then proceeded to line the interior surface of 
these with the powdered fish-scales, which he called essence 
of pearl, or essence & Orient. This was rendered adhesive by 
being mixed with a solution of isinglass, when it was intro- 
duced in a heated state inside the globules, and spread over the 
whole interior surface, by shaking the beads which, for thai 
purpose, were placed in a bowl upon the table. These hollow 
beads being blown exceedingly thin, in order to produce a bet- 
ter effect, were consequently very tender. To remedy thi 
evil, as soon as the pearly varnish was sufficiently dry, they 
were filled with white wax, and being then bored through with 
a needle, were threaded for sale. 

An expert workman can blow from five to six thousand smal 
glass globules in a day ; but, as some attention is called for m 
regard to the shape and appearance of these beads, the produce 
of a man's daily labor will not much exceed one fourth of that 
quantity. The closer to counterfeit nature in their manufacture 



* Hist, of Inventions, vol. ii. art. Artificial Pearls. 






CHAP. IX. MOCK PEARLS. 

these beads are sometimes purposely made with blemishes, arid 
of somewhat irregular forms. Some are made pear-shaped; 
others are elongated like olives ; and others again are flattened 
on one side, in imitation of natural pearls, which are set in a 
manner to show only one side. 

The fish whose scales are put to this use are about four 
inches in length. They are found in great abundance in some 
rivers ; and, being exceedingly voracious, suffer themselves to 
be taken without difficulty. The scales furnished by 250 of 
these fish will not weigh more than an ounce, and this will not 
yield more than a fourth of that quantity of the pearly powder 
applicable to the preparation of beads ; so that 16,000 fish are re- 
quired in order to obtain only one pound of the essence of pearl. 

Up to a recent period, the heirs of Jaquin, the first inventor, 
carried on a considerable manufactory of these mock pearls ia 
Paris. The fish are tolerably abundant in the river Seine ; but 
their scales are conveyed from distant parts in much larger 
quantities than can be procured on the spot, for which purpose 
they are preserved in volatile alkali. 

The dial-plates of clocks and watches are made of opaque 
white glass, which has acquired the name of enamel. The pe- 
culiarly delicate appearance of these, as well as their opaque- 
ness, result from the presence of oxide of tin. 

These plates, which are not of greater diameter than twelve 
inches, are made in one piece ; but any which are required to 
be larger than this, must be formed in separate segments, and 
afterwards joined together. 

In the preparation of dial-plates, the first process is that of 
hammering a thin plate of copper of the requisite size upon a 
slightly concave anvil constructed of hard wood ; for which 
operation a convex hammer is employed, and in this manner 
the proper state of convexity is imparted to the plate, without 
impairing in any degree the smoothness of its surface. 

The centre hole for the hour and minute hands, as well as 
that whereby the key must be introduced for the purpose of 
winding up the clock or watch, together with other smaller 
holes, for the screws by which the dial is to be attached to the 
works, are all made by passing tools of appropriate forms and 
sizes through the copper, from the concave side, in such a man- 
ner that the metal displaced in the act may form ridges round 
the holes on the convex side, and be instrumental in retaining 
the enamel to the requisite thickness upon the surface, when 
in its state of fusion. For this same purpose, the outside edge 
of the plate is hammered up all round, so as to form a ridge of 
the requisite depth; and provision must be made for this rim 

Q2 



GLASS MANUFACTURE. CHAP. IX. 

in the ske originally given to the copper. The metallic plate 
thus formed is thoroughly cleansed by being immersed in a 
weak dilution of nitric acid, after which it is dipped in pure 
water, and rubbed smartly over with a brush formed of brass 
wires. 

The white enamel is then broken in a hardened steel mor- 
tar, until it is reduced to fragments about the size of fine 
sand ; and the whole should be brought as nearly as possible to 
the same state as regards the size of the particles. The pounded 
glass is then washed in very clear water, and the heavier parts 
having subsided, the remaining milky-looking liquid is poured 
off and left to settle in a separate vessel. This operation is 
several times repeated ; so that the powder may be divided into 
separate portions, having different degrees of fineness. 

The enamel being thus sorted and well washed, the separate 
portions are placed in glass vessels, and nitric acid is poured 
over, so as completely to cover the powders. The acid must 
be left on the enamel during the space of twelve hours, the 
whole being occasionally stirred with a glass spatula, in order 
to dissolve away any metallic particles which may have been 
abraded from the steel mortar, and which would greatly impair 
the whiteness of the enamel when subsequently applied on the 
face of the plate. The acid is then poured ofTJ and the enamel 
washed in successive waters, until it no longer contains any 
acidity ; after which, it is again covered with pure water, and 
in this state it must remain until used, that its perfect white- 
ness and purity may be preserved. 

It is necessary to operate upon both sides of the plate, lest 
the heat of the enamel, when in a state of fusion on the con- 
vex side, should alter the curvature of the copper, and deform 
its shape. 

The enamel, when prepared in the manner described, is first 
applied to the concave or under face ; in which process the 
artist spreads over it with a spatula, as thin and as evenly as 
possible, a portion of the finer settlings. A tool which had pre- 
viously been i userted in the centre hole is then withdrawn, and 
its place supplied with a rag of clean linen, which absorbs all 
the superfluous water from the enamel, bringing it to such a 
state of consistency, that this, which is called the counter-en- 
amelling, will adhere sufficiently to the copper when the posi- 
tion of the plate shall be reversed. In then proceeding to op- 
erate upon the convex surface, the plate must be turned over, 
a tool being again placed in the centre hole, and a layer of the 
coarser part of the pounded glass thereafter applied with every 
possible care as to the evenness of its distribution. It is par- 
ticularly requisite to cover well the edges of the dial-plate, as 



CHAP. IX. DIAL PLATES. 187 

well as those of the different holes, lest the heat should after- 
wards act too powerfully upon the metal. To draw off the su- 
perfluous moisture from this layer of enamel, a fine linen cloth 
is applied round the entire edge, which, in this altered position 
of the dial, is now its lowest part, and has in that respect taken 
the place of the centre hole in the counter-enamelling process 
first mentioned. In order that the particles may arrange them- 
selves properly and closely together, the tool still remaining in 
the centre hole is then subjected to two or three slight concus- 
sions, and much of the beautiful appearance of the finished 
dial-plate depends upon the neatness with which this operation 
is performed. If the enamel is evenly spread and well packed 
together, no hollows will be left below the surface when it has 
been melted, and the requisite degree of smoothness will be at- 
tained. To dissipate any moisture w T hich may now be retained 
by the enamel, the plate is dried on a sheet of iron over a 
chafing-dish. 

The dial-plate, thus prepared, is introduced cautiously and 
by degrees under a muffle placed in a furnace, it being neces- 
sary to heat it gradually : in this situation it must remain until 
it is perceived that the enamel begins to melt ; the sheet of 
iron on which the dial is placed should then be turned gently 
round, in order that every part may be equally exposed to the 
heat of the muffle. So soon as the enamel is seen to be per- 
fectly melted over the whole surface, the plate must be with- 
drawn with as much caution and deliberateness as w T as used 
upon its introduction ; and, in order to prevent the cracking 
and scaling off to which the glass would otherwise be liable, 
the plate must remain for some time cooling very gradually at 
the mouth of the muffle. The necessity for this delay in the 
process arises from the same physical law which obliges the 
manufacturer to have recourse in larger operations to the 
annealing oven. 

When this first firing has been completed, the plate must be 
cleaned, as before, with a very weak dilution of nitric acid ; 
and a layer of the finer settlings of the enamel is to be spread, 
in the manner already described, over the convex side. It is 
uot necessary to apply any further coating to the inner or con- 
cave surface, unless upon examination any part of the former 
layer shall appear defective ; in which case such part must be 
made good with a further portion of the same division of the 
enamel as was used before. 

The same precautions that were observed in the first firing 
for placing the dial-plate within, and for removing it from the 
muffle, must be repeated now ; and must equally be practised 
when a third layer, which must be 'of the finest and whitest 



188 GLASS MANUFACTURE. CHAP. IX. 

portion of the enamel, is subsequently spread over the convex 
side. When this third layer has in its turn been fused and 
gradually cooled, the dial-plate is complete, with the exception 
of the figures or lettering, which must be placed upon the con 
vex side to mark the divisions of the hours and minutes, and 
which are thus applied : — 

A black enamel, which is so composed that it will fuse at a 
lower degree of heat than the white opaque glass already em 
ployed, is to be ground exceedingly fine in an agate mortar 
with a pestle of the same substance, and in combination with 
oil of lavender ; which, as it would of itself be too thick, must 
have its consistence reduced by the addition of oil of turpentine. 
To such an exceeding degree of fineness is it considered ne 
cessary to reduce this black enamel for the purpose, that the 
labor of half a day is usually employed in thus grinding a drachm 
weight. A further quantity of the mixed essential oils must 
afterwards be added, that the enamel may be sufficiently thin 
to flow readily from the pencil. « 

The dial-plate is then placed upon some level surface, and 
by means of a pair of compasses, having one of the legs blunt 
at the end and rounded, so that it will freely turn in the centre 
hole where it is placed, and the other leg provided with a black- 
lead pencil, two circular lines are slightly traced at unequal 
distances from the centre, between which the numerals are to 
be inserted. The exact position of these is determined by 
means of a sector furnished with a movable limb ; and the dif- 
ferent figures being drawn with a camel's hair pencil charged 
with the prepared black enamel, this is left to become pefectly 
dry in the air ; and its fusion having afterwards been effected 
in the muffle, the dial-plate is completed, and in a fit state to 
be placed in the hands of the clockmaker. 



CHAP. X. FORMATION OF LENSES. 189 

CHAP. X. 

ON THE FORMATION OF LENSES. 

Preparations of the necessary Tools.— Choice of Glass.— Grinding.— Polish- 
ing.— Curdled Lenses. — Means used for avoiding this Defect. 

In grinding glass for spectacles, or preparing them as lenses 
for optical instruments, the first thing to be attended to is to de- 
termine the proper focal distance of the glass. Taking then a 
pair of compasses, which, on the supposition that the glass is 
intended to be convex or concave on both sides, must be opened 
to the full focal distance ; two arches or segments of circles, 
each extended somewhat beyond the breadth which it is in- 
tended to give to the glass, must be described upon a piece of 
sheet copper, which must then be filed away from the out- 
side of one and from the inside of the other arch. By this 
means two gauges are formed, the one convex and the other 
concave, and each perfectly answering to the other. 

If it is intended that the glass shall be what the opticians call 
plano-convex or plano-concave, that is, having one of its sides 
flat, while the other has received the requisite curvature, the 
compasses wherewith the arches are described should be opened 
to only one half the focal distance. 

Two circular plates of brass, about one-tenth of an inch in 
thickness, and each being of a little larger diameter than the 
intended lenses, are then securely soldered upon a cylindrical 
piece of lead of an equal diameter with the brass discs, and one 
inch in thickness ; these, which are called tools, are then fixed 
in the lathe, and turned so as to correspond with the copper 
gauges, the surface of one being made convex, and of the other 
concave. 

The two brass discs are then to be ground together with 
emery, or with pounded Turkey-stone, until their surfaces ex- 
actly coincide in every point. 

If the focal distance is very short, so that the convexity and 
concavity require to be very considerable, the brass discs should 
be hammered as nearly as possible to their intended form be- 
fore they are soldered to the leaden cylinders, and turned; 
otherwise either the thickness of the brasses would require to 
be inconveniently increased, or the more considerable portion of 
their substance, which must in such case be cut away, would 
occasion the discs to be too thin and yielding. 

The glass of which a lens is composed is chosen with refer- 
ence to the purpose to which it is to be applied, and according 
to its refractive and dispersive powers : its selection must be 



190 GLASS MANUFACTURE. CHAP. X. 

left to the discretion of the optician. Its two surfaces should 
originally be perfectly parallel. Being cut or clipped into a 
circular form by means of scissors or pincers, the edge must be 
smoothed on a common grindstone, and the glass fixed by seat- 
ing one of its surfaces in softened pitch on the flat end of a solid, 
cylindrical, wooden handle of smaller diameter than the glass, 
The centre of the axis of this handle must coincide exactly with 
the centre of the glass. 

If, to suit a short focal distance, the curvature of the lens re- 
quires to be great, it will simplify the labor of the artist, if, pre- 
viously to its being thus fitted to its handle, the glass is reduced 
upon the grindstone as nearly as possible to the shape of the 
gauge. Some judgment is, however, necessary in this process, 
lest the abrasion should be carried too far, even in any one mi- 
nute point, which would render the glass wholly unserviceable. 

The convex form is that which is most commonly given to 
lenses; and in describing the process for effecting this, the 
mode of producing concave glasses will equally be understood ; 
the only difference between the two methods being this, — that 
in the first operation, the concave tool and gauge are brought 
into use ; while for the other, those having a convex form are 
employed. 

The whole being thus prepared, the concave tool is fixed 
firmly on the working bench; and having some fine emery 
sprinkled on its surface, the glass is worked upon it with circu- 
lar and cross strokes alternately ; the artist being careful that 
the centre of the glass shall never pass beyond the edge of the 
tool. 

When by these means the glass has been so far ground that 
its surface coincides with that of the tool at every point, the 
emery is to be washed away, and some of the finer kind substi- 
tuted ; and so on through three or four different degrees of fine- 
ness, until all the roughnesses and apparent scratches on the 
glass are worn down, and it has become perfectly smooth to the 
touch, although dull and opaque to the eye: after this it is 
sometimes further ground with finely pounded pumice-stone. 

At the expiration of every five or six minutes, during this 
grinding process, the surface of the tool is rubbed for a short 
time within the concave tool, that its proper curvature may be 
perfectly preserved. When the operation has been completed, 
the glass is easily separated from its wooden handle by means 
of a thin knife, and the pitch is removed by rubbing it with oil. 
The side which has been ground is, in its turn, fixed upon the 
wooden handle, and the other side is then ground in the same 
manner as the first. 

Convex glasses are frequently prepared for common purposes, 



GHAP. X. POLISHING LENSES* 191 

in another manner. The concave tool is fixed upon the lathe, 
and the glass being held steadily in the hand, and sprinkled 
with emery, is applied to the tool during its revolutions. For 
concave glasses, the convex tool is fitted to the lathe, and the 
glass is in like manner presented to it ; but this method, although 
easier and more expeditious, is greatly inferior in its result to 
hand-grinding, and cannot be resorted to when any thing like 
perfectness in the intended instrument is desired. 

The same brass tool which is used for grinding, serves also 
for polishing lenses ; but before it is thus employed, a smooth 
thick piece of felt must be stretched over and cemented to it, 
and the outer surface being then covered with washed putty 
powder, which is a combination of the oxides of tin and lead, 
the tool is worked upon the lens with the same motions as are 
employed in grinding it. The consistency of the powder is a 
point requiring attention ; for if it be too moist, it will cause 
the fibres of the felt to rise up and polish, not only the surface, 
properly speaking, but likewise the innumerable hollows, which, 
notwithstanding all appearances to the contrary, are actually 
left in the surface from the grinding. If the lens be subjected 
to examination in a microscope, this effect will be rendered 
fully apparent. The evil consequence resulting from this de- 
fect is, that the cavities being polished, admit the rays of light, 
and disperse, instead of collecting them, as would be the case 
if the surface were uniform. When this fault exists in a de- 
gree so exaggerated as to be visible to the naked eye, the lens 
is said to be curdled. 

An excellent method has lately been adopted by an eminent 
optician in London, whereby this defect is avoided. Bees' 
wax is hardened to a proper degree by admixture with dry red 
sulphate of iron, which has previously been carefully washed ; 
and instead of the covering of felt, this compound is melted 
over the brass tool. When cold, the casing thus formed is suf- 
ficiently hardened to be. turned to the required curvature, and 
the tool, when this has been done, is in a fit state for use. 

The peculiar advantage of this compound, as a polishing 
substance, consists in its perfect uniformity ; besides which, it 
las this further recommendation, that if any hard particles 
should accidentally insinuate themselves between the tool and 
the lens, and which in other circumstances would scratch the 
glass, the wax is sufficiently yielding to allow them to bury 
themselves in its substance, so that all injury of this kind is 
voided. 

-Lenses which have been thus treated, will bear examination 
with a microscope, their polish appearing uniformly clear and 
defined. 



192 GLASS MANUFACTURE. CHAP. X. 

Convex lenses in their simple state have been used for col- 
lecting the heating rays of the sun, or for forming what are 
called burning-glasses. One of the largest lenses ever applied 
to this purpose was made of flint glass by Mr. Parker. The 
diameter of this glass was 3 feet; its focal distance was 45 
inches ; and the circular spot of light which it cast at the focal 
point was 1 inch in diameter. Still farther, and as much as 
possible to condense the rays, Mr. Parker employed a smaller 
lens, 13 inches in diameter, in conjunction with the larger one, 
and by means of this the heating rays were concentrated at 
the focal point to f of an inch. The effects produced by this 
arrangement were surprising: 20 grains of pure gold were 
fused in 4 seconds; the same effect was produced on 10 grains 
of platina in 3 seconds; and a diamond, whose weight was 10 
grains, was found to have lost 4 grains after having been placed 
within the focus during 30 minutes. 

This lens, which cost, 700Z., has since passed into the posses- 
sion of the emperor of China. 



CHAP. XI. 

ON THE PRINCIPAL DEFECTS OBSERVABLE IN GLASS. 

Strife— Render Glass unfit for Optical Purposes. — Threads — Render Glass 
fragile.— Cause of this.— Tears— One of the greatest Defects.— Render 
Glass useless.— Knots.— Bubbles.— Whence they proceed.— Do not much 
affect the Quality of Glass. — Objects to be attained for avoiding these De- 
fects.— M. Guinand. — His humble Origin. — Energy of Character. — Exam- 
ines Telescopes, and constructs others. — Unable to procure Glass of good 
Quality. — Is incited to examine into the Causes of Inferiority.— His ex- 
traordinary Perseverance amidst Accidents and Difficulties. — His ultimate 
Success. — Accident leading to further Improvement. — Prosecutes his art 
in Bavaria. — Returns to Switzerland, and further pursues his favorite Ob- 
ject. — Dies. — Frauenhofer. — Rises from Obscurity by his Talents. — His 
Scientific Acquirements. — Produces Specimens of perfect Glass. — Dies at 
an early Age. — Respect paid to his Memory. 

The principal defects observable in manufactured glass, are 
stricB, threads, tears, and knots. These, when they occur to 
any extent, all impair its beauty, and some of them injure its 
actual quality. Although it is not difficult to attain such an 
amount of proficiency in the manufacture as will preserve the 
materials from these evils in their extreme degree, yet, alto- 
gether to avoid their occurrence, and to obtain glass of a per- 
fect quality, is a task that long, and with only doubtful success, 
has engaged the thoughts and labors of men devoted to scien- 
tific pursuits. The difficulties that attend the attainment of 
this object are sufficiently proved by the fact that, during ten 
years, one of the most considerable and most scientific opticians 



CHAP. XI* DEFECTS IN GLASS* 193 

in London has been disappointed in his efforts to procure a disc 
of flint glass only five inches in diameter, sufficiently fitted, by 
the absence of defects, to be employed in the construction of a 
telescope. 

Striae are undulating appearances, perfectly vitrified, and 
equally transparent with any other part of the glass : they do 
not occasion any roughness or inequality in the surface, but re- 
sult from a want of congruity in the composition of the parti- 
cles which make up the substance : in other words, the struc- 
ture is not perfectly homogeneous ; and although each different 
portion may be altogether good in itself, and the whole mass, 
if made up of any one of these portions, would be equally per- 
fect in itself, yet, the whole acting without any uniformity, the 
rays of light in passing through them are bent or refracted 
differently, and the objects beyond appear distorted. 

This condition must exist to a considerable extent to be easi- 
ly discernible by the naked eye, or detrimental to the quality 
of the glass, when applied to the more ordinary purposes of 
use or ornament ; but glass striated in a scarcely perceptible 
degree, is yet wholly inapplicable to the construction of optical 
instruments, where the objects they are intended to present to 
the eye will be many times magnified ; and where, consequent- 
ly, every defect or distortion that accompanies their transmis- 
sion through the glass will be equally enlarged. The end pro- 
posed in the employment of these philosophical instruments, is 
the minutely accurate examination of distant or very diminu- 
tive objects ; and this purpose it is evident must be completely 
frustrated, by the defect here described. 

The name of threads is usually given to fibrous appearances 
in the body of the glass, which result from the vitrification of 
clay. Their color is greener than that of the rest of the glass. 
~hreads, if existing in great numbers, render the material ex- 
tremely fragile ; and the same effect is produced, if, although 
fewer in number, the threads are individually larger. The 
cause of this increased brittleness is, that the dilation and con- 
traction, at different temperatures, of glass, which results from 
the fusion of clay, differ from those of glass made with silice- 
ous sand ; for which reason, each in turn exerts a hurtful influ- 
ence upon the other. 
Tears are, perhaps, the greatest defect that can be found in 
lass. They are in fact an exaggeration of the imperfection 
ast described, and usually proceed from the fusion and vitrifi- 
cation of portions of the clay that forms the arch of the fur- 
ace, and which are suffered to drop into the pots, and to float 
n the glass while in its state of fusion. Wherever these tears 
xist, the material is brittle in a very high degree, so as fre- 

R 



194 GLASS MANUFACTURE. CHA] 

quently to crack, without any apparent cause, by the me 
feet of the unequal expansion just described, which accid> 
more likely to occur in proportion as the drops are near 
the surface. This defect is one of so serious a nature, tl 
is usual, on discovering its existence, at once to throw 
the glass as useless. In places where, as is frequently the 
in England, covered crucibles are employed, this accident k 
a great degree avoided. 

Three kinds of knots are observable in glass ; one of these 
arises from the aggregation of several imperfectly vitrified 
grains of sand. Another is owing to some portions of glass 
gall not having been removed during the refining; and the 
third kind is produced by any small parts of the crucible or of 
the furnace which, having been abraded by the rubbing of the 
tools or other accidental circumstance, have fallen into the 
glass. 

Small bubbles are frequently seen abundantly spread through- 
out the substance of the glass. These indicate an imperfect 
degree of refining, and proceed from the disengagement of 
gas which occurs during the process of vitrification. Their 
presence announces that the glass has not been sufficiently fluid 
in the course of its refining to allow of their dispersion. Thi 
may happen through one of two causes, either that a sufficient 
amount of fluxing material has not been used with the sand 
or that the fire has not been sufficiently intense for the due 
liquefaction of the compound. These bubbles are chiefly ob- 
jectionable on account of their unsightly appearance, and d< 
not really deteriorate the quality of the glass even for optica 
purposes. In this case each bubble acts as a small convex lens 
rapidly turning aside the rays which strike against it, and oc- 
casioning a diminution of light in proportion to its area. Bu 
when these bubbles are even numerous, the sum of theii 
united areas will amount to only a small proportion of the 
whole surface of the glass; and the loss of light will be incon- 
siderable.* 

It thus appears that the principal object to be sought after ii 
the manufacture of perfectly homogeneous glass is, to avoic 
those variations in the composition and specific gravity of it 
different parts, which occasion the striated appearance de- 
scribed above. To enter minutely, and at length, into a con 
sideration of the means that have been proposed and adoptee 
with a view to remedy this considerable evil, would presen 
little that is amusing to the general reader ; while those per 
sons who feel any particular interest in the subject, or whos 



Mr. Faraday, Bakerian Lect. ; Phil. Trans. 1830, p. 7. 



CHAP. XI. M. GUINAND. 195 

taste for scientific research leads them to admire the detail of 
well considered and ably conducted plans for the mastery of a 
difficult operation, may gratify themselves by consulting Mr, 
Faraday's truly valuable paper already referred to, and which 
will be found comprised in the Philosophical Transactions for 
the year 1830. 

Some exceedingly favorable specimens of glass for optical 
purposes have lately been prepared by Mr. Green, the proprie- 
tor of the Stangate Glass-house ; a gentleman whose personal 
attention has been unintermittingly given during many years 
to all the practical operations and details of an extensive es- 
ablishment. Mr. Green is far from asserting that in what has 
een accomplished he has arrived at any certainty in the solu- 
tion of this difficult problem, and feels that at most he has 
litherto made only an approach to it; while, however, it is 
uch an approach as justifies the hope, that, through continued 
lought and exertion, a still greater and more important de- 
;Tee of perfection may be attained. 

The circumstances which attended the long-continued and 
aborious investigations on this subject of another and a very 
sxtraordinary man, are, in themselves, so curious and interest- 
ng, and seem likely to be followed by such important conse- 
uences, to at least one branch of the art, that a treatise on the 
anufacture of glass might be justly charged with incomplete- 
ess, if it did not furnish at least a sketch of those circum- 
tances. 
The following account is condensed from a memoir, read at 
sitting of the Society of Physics and Natural History of Ge- 
eva, on the 19th of February, 1823, as given in the nineteenth 
lume of the Quarterly Journal of Science, published in Lon- 
n in the year 1825. 

The late M. Guinand was born in an inconsiderable village, 
■nong the mountains of Neufchatel in Switzerland. His father 
r as by trade a joiner, and must have been in very indifferent 
rcumstances, as his son was called upon to assist him when 
dy ten years old, and without having acquired more than a 
;ry imperfect knowledge of the first rudiments of learning ; 
deficiency which was never afterwards supplied, as M. Gui- 
md always read with difficulty, and wrote very imperfectly, 
e must, even at this early period, have been a lad of consid- 
•able talent, and of a disposition that urged him to the exer- 
n requisite for raising his condition in society. We find 
m, when between thirteen and fourteen years old, having 
itted the employment of a joiner for that of a cabinet-maker, 
iefly engaged in making cases for clocks. At this period he 
quired from an acquaintance some knowledge of the art of 



196 GLASS MANUFACTURE. CHAP. XI. 

casting and working in metals, of which knowledge he after- 
wards availed himself by adopting, when twenty years of age, 
the occupation of a watch-case maker, the manufacture of 
watches forming a very considerable branch of industry in that 
part of the country. 

At the house of a person for whom he then worked, M. J. 
Droz, the constructor of several automaton figures, which forty 
years ago made the tour of Europe, young Guinand enjoyed 
an opportunity of seeing for the first time a very fine reflecting 
telescope which had been made in England, and which at once 
appeared to him so curious and interesting an object, that he 
petitioned for and obtained leave to take it in pieces, the more 
minutely to examine its construction. The use made of this 
permission was soon rendered apparent by the production of a 
similar telescope ; and this, which he had constructed with his 
own hands, on being examined by many competent persons, 
was pronounced by them to be equal in excellence to that 
which had served him as a pattern. 

Surprised at this success, the gentleman to whose kindness 
he owed this opportunity questioned the artist as to his ac- 
quaintance with the science of optics, and in particular to what 
treatise he was indebted for his proficiency. The surprise of 
M. Droz was naturally increased on learning that the instru- 
ment had been produced without any knowledge whatever of 
the theory of optics, and with no more acquaintance with the 
practice of the art than had been acquired through the exam- 
ination of the English instrument. M. Droz immediately placed 
a treatise on the subject in the hands of the young man, which 
he rather deciphered than read ; but the substance of which 
was imbibed by him so completely, that he was enabled, afte 
witnessing the making of one pair of spectacles, to form and 
polish lenses, and to make spectacles for himself and others, 
which were pronounced to be excellent. His principal amuse- 
ment at this time was found in manufacturing telescopes, which 
he got up at a cheap rate, forming the tubes of pasteboard. 

When the important discovery of achromatic glasses reaches 
Switzerland, Guinand's mind was very strongly excited by it ; 
and M. Droz having obtained a telescope of the new construc- 
tion, again permitted the young man to examine its varioui 
parts and structure. The very imperfect state of the arts at 
that time in Switzerland, and the deficient means of Guinand 
prevented his achieving the construction of a similar instru- 
ment. He was unable to produce glasses of different refractive 
power; and it was not until several years after that an ac 
quaintance, making a visit to England, conveyed to him a piece 
of flint glass, with which, although it was by no means void of 



CHAP. XI. M. GUINAND. 197 

imperfections, being considerably striated, he succeeded in 
making some tolerably good achromatic glasses. Finding that 
not only the glass which he had himself worked, but that every 
other specimen which he examined was thus imperfect, he was 
incited to a more particular scrutiny into the subject, and bring- 
ing into action all the knowledge he had acquired in the art of 
fusion, he melted in his furnace the fragments of his flint glass. 
All the satisfaction derived from this experiment was the ac- 
quirement of some degree of knowledge as to the composition 
of flint glass, some particles of lead being revived in the metal- 
lic state during the process. Guinand was thirty-five years old 
at the time when this fresh incitement led to his seeking after 
such chemical knowledge as might assist him in experiments 
on vitrification, and his evenings' employment during six or 
seven years was to melt in his blast furnace a few pounds' 
weight of glass, carefully noting down every circumstance at- 
tending each experiment, that he might be enabled to continue 
such as afforded any prospect of advantage, and to avoid others 
which had a contrary tendency. 

These small experiments led to no decisive results ; and he 
was upwards of forty years old when, having undertaken a 
new and more profitable trade, that of making bells for repeat- 
ing-watches, he was enabled to devote more of his earnings to 
the prosecution of experiments, which he thenceforth under- 
took upon a scale more likely by their results to reward his 
perseverance. 

In this pursuit he was still exposed to numerous accidents 
and difficulties, which would have deterred most persons from 
continuing the research. His furnace, which he had con- 
structed with his own hands, out of such materials as he could 
procure, and which was capable of melting at once 200 lbs. 
w T eight of glass, proved defective. He was then obliged to pro- 
cure materials for the purpose from abroad ; and having once 
more completed its erection, and consumed much fuel in heat- 
ing it, had the mortification to find that it still required altera- 
tion. Then his crucibles, which he was equally obliged to form 
with materials ill-qualified for the object, cracked during the 
process, and the vitreous matter was lost among the ashes of 
his furnace. Although during all this time his family arrange- 
ments were formed upon a plan of the most rigid economy, he 
was compelled to employ an interval between each one of his 
experiments in earning at his regular employment sufficient 
means for subsistence, and for providing the apparatus, mate- 
rials, and fuel needful for renewing them. 

All this time the pursuit had laid hold so completely of his 
mind, that he was deprived of his natural rest while considering 

R2 



198 GLASS MANUFACTURE. CHAP. XI. 

upon the causes of his various failures, and endeavoring to rea- 
son out the means for their prevention. 

Having at length succeeded in obtaining a block of glass 
weighing about 200 pounds, and having sawn it into two verti- 
cal sections, he polished one of the faces, in order, as far as 
possible, to examine the circumstances produced by the fusion. 

To account for the numerous and various defects exhibited 
by this specimen, M. Guinand formed a theory which he made 
the groundwork of his future operations. A more intimate 
knowledge of those defects, and a conviction thus attained of 
the great difficulties opposed to their removal, instead of damp- 
ing his ardor in the pursuit, served to infuse new energy into 
his mind. Nor was he mistaken in his estimate of the obstacles 
to be surmounted ; " so that," as he himself declared, " the 
sacrifices and exertions which he had previously made were 
trifling when compared with those which he afterwards under- 
went for the purpose of removing these various defects, and of 
rendering his glass homogeneous." 

The steps through which he pursued this arduous under- 
taking, and the methods by which its success was accomplished, 
it is not possible to detail. All that is publicly known upon the 
subject is, that he succeeded in discovering a mode of proceed- 
ing which gave the almost certainty of producing in the fusion 
of a pot containing from 200 to 400 pounds of glass, one half 
at least of its substance entirely homogeneous, and therefore 
fitted for the construction of perfect optical instruments. With 
this result, satisfactory as it would have been to most men, 
Guinand expressed himself by no means contented, and con- 
tinued his researches, without, however, ever arriving much 
nearer to perfection in the art. 

He was now enabled to make for use discs of glass perfectly 
homogeneous, with a diameter of twelve inches; a great 
achievement, when compared with what had been at any time 
accomplished by others. 

On one occasion the artist had succeeded, through much 
carefulness and exertion, in obtaining a disc eighteen inches in 
diameter, and of a quality perfectly satisfactory. This was al- 
ready finished and placed in the annealing oven to cool gradu- 
ally, when, through some unaccountable accident, the fire 
caught the roof of his humble dwelling. With some trouble 
the flames were extinguished ; but the water used for this pur- 
pose had found its way into the oven, and the precious deposit 
was destroyed. It is said that the discouragement caused by 
this accident prevented M. Guinand from afterwards attempting 
any similarly extensive experiment. He entertained no doubt, 
however, that, with means for operating on a larger scale than 



CHAP. XI. M. GUINAND. 199 

he could accomplish, lenses of double or even triple the diame- 
ter here mentioned might be produced. 

For some time after he had thus far succeeded in his object, 
M. Guinand was accustomed to divide his blocks of glass by 
that which appeared the only fitting method, sawing them into 
sections perpendicular to their axis, polishing the sections, and 
then selecting such parts as were adapted to his purpose, re- 
turning the remaining portions to the crucible for future opera- 
tions. By this means he had frequently the mortification of per- 
ceiving that the glass was divided, so as to present a less ex- 
tended surface of perfect material than the state of the block 
would, if previously known, have rendered possible ; and he 
was frequently able to procure discs of only small diameter, 
when, could he have been fully aware of the particular circum- 
stances of the glass throughout its substance, he might, by cut- 
ting in another direction, have obtained a more satisfactory re- 
sult. 

This disadvantage was remedied in a way apparently as un- 
toward as it was singular and unexpected. While his men 
were one day carrying a block of glass on a hand-barrow to a 
water saw-mill, which he had constructed at the fall of the 
river Doubs, a short distance from his dwelling, the mass acci- 
dently slipped, and, rolling to the bottom of a rocky declivity, 
was broken into several pieces. Endeavoring to make the best 
of this seeming misfortune, such fragments of glass were se- 
lected for operation as appeared to be fitted by their homoge- 
neity for the purpose; and these were softened in circular 
moulds, in such a manner that they furnished discs of a very 
satisfactory quality. Further examination enabled Guinand to 
perceive that the fracture had in a great measure followed the 
variations of density in the glass ; and, pursuing the idea thus 
obtained, the artist thenceforth adhered to a method so singu- 
larly in the first instance forced upon him. 

After this, M. Guinand contrived a mode of cleaving the 
glass while cooling, so that the fracture accompanied the direc- 
tion of the more faulty parts ; by which course he frequently 
obtained masses of glass which were absolutely homogeneous, 
weighing from forty to fifty pounds. These masses, cleft again 
by means of wedges into pieces of convenient shape, were re- 
melted in moulds which gave them the form of discs ; an ope- 
ration which differs essentially from that used by other glass- 
makers. 

Several years of his life were thus employed by this extraor- 
dinary man in making bells for repeating-watches, and con- 
structing achromatic telescopes with glass of his own prepar- 
ing. The retired spot wherein he- resided, offered only very 



200 GLASS MANUFACTURE. CHAP. XI. 

limited opportunities for acquiring a reputation in -the world ; 
yet, by degrees, the superior value of his labors became appre- 
ciated, and he was visited by such men of science as travelled 
into the neighborhood of his dwelling. By one of these, a 
knowledge of his merits was conveyed to M. Frauenhofer, the 
chief of a celebrated manufactory for optical instruments, es- 
tablished at Benedictbeurn in Bavaria. This gentleman having 
in consequence obtained sOme discs of glass made by Guinand, 
found their quality so satisfactory, that he repaired in person to 
Brenets, where the artist resided, and engaged him to settle in 
Bavaria. This was in 1805, when Guinand was upwards of 
sixty years of age. He continued at Benedictbeurn during nine 
years, occupied solely in the manufacture of glass, to the great 
increase of M. Frauenhofer' s reputation. 

Being desirous, at the end of this time, to return to his native 
land, a pension was granted to him by the establishment, on 
condition that he should no longer employ himself in making 
glass, nor disclose his process to any person whatever ; a con- 
dition which did not long agree with the still active energies 
of his mind. Believing that by new experiments he could raise 
his discovery to a yet higher degree of improvement, he obtain- 
ed the consent of M. Frauenhofer to cancel their subsisting 
agreement ; and relinquishing his pension, once again devoted 
himself with ardor to his favorite pursuit. 

M. Guinand lived for several years after this time (1816,) 
and produced several telescopes of great magnitude, and re- 
markable for their excellence ; it being perhaps not the least 
extraordinary among the circumstances attending them, that, 
to use the words of the memoir, whence the foregoing account 
is drawn, " they have been constructed by an old man upwards 
of seventy, who himself manufactures the flint and crown glass 
which he uses in their construction, after having made with his 
own hands the vitrifying furnace and his crucibles ; who, with- 
out any mathematical knowledge, devises a graphic method of 
ascertaining the proportions of the curves that must be given 
to the lenses, afterwards works and polishes them by means pe- 
culiar to himself; and lastly, constructs all the parts of the dif- 
ferent mountings, either with joints or on stands, melts and 
turns the plates, solders the tubes, prepares the wood, and com- 
pounds the varnish." 

Arrangements had been made by the French government 
for purchasing his secret, when the artist, verging on his eigh- 
tieth year, died, after a short illness. That secret did not, how- 
ever, die with him, but is possessed by his 4 son, who continues 
to labor in the employment so singularly commenced, and so 
successfully and energetically followed by his father. 



CHAP. XI. M. GUINAND. 201 

The name of Frauenhofer, which has been introduced in the 
foregoing narrative, is one intimately connected with inquiries 
in the art of making perfect glass, It would be wrong to leave 
the reader under an impression that the merit of this artist was 
limited to the single act of patronage extended towards Gui- 
nand, and which, although indicative of his discernment as a 
tradesman, would afford no reason for investing him with any 
part of the extraordinary merit which truly belonged to his 
character. 

Like Guinand, his beginning in life was humble ; being in- 
debted solely to the powers of his own mind for the eminence 
to which he attained. Having occupied the lowest station as an 
ordinary workman in a great manufacturing establishment, he, 
by the force of his transcendent talents, and in the course of a 
few years, raised himself to the chief direction of its business. 
During the intervals of labor he acquired a competent know- 
ledge of mathematical science ; and devoting himself to the per- 
fection of the refracting telescope, proved that he possessed a 
truly philosophical and scientific mind. Having soon mastered 
the theoretical difficulties which presented themselves, he still, 
however, found all his labors unavailing, through the imperfec- 
tion of the material employed ; and set himself to remedy this 
evil, by a series of admirable experiments. 

It might be thought invidious to inquire in what degree his 
success in these was owing to the previous labors and assist- 
ance of Guinand, or how far his discoveries were personal and 
original. Both produced and left behind them specimens of 
perfect glass in large pieces ; but the public has equally in 
either case to regret the want of knowledge as to the processes 
employed for the attainment of an object so desirable. 

Frauenhofer died in the year 1826, at an early age ; a victim, 
it is said, to unremitting attention bestowed upon an unhealthy 
employment. Had his life been continued to the same length- 
ened period as was allotted to his fellow-laborer, what might 
not the world have expected from one, who so early had burst 
the chains of ignorance, and overcome the paralyzing difficul- 
ties of birth and adverse fortune ; taking his station during 
life among the genuine philosophers of the age, and falling, 
admired, and lamented, and eulogized by the most scientific 
societies of Europe ! 

The great value of flint glass, from which all perceptible 
defects are absent, may be imagined from the sketch which 
has here been given of the efforts made for its production. 
Very high prices are, in fact, paid for object glasses of a satis- 
factory quality, which are of any magnitude ; while even small 
fragments of such glass are sought after by opticians with 



202 GLASS MANUFACTURE. CHAP. XI. 

great avidity. A few years ago the director of one of the 
London glass-houses having made a pot of flint glass for optical 
purposes, sold this, in the regular course of his business, to a 
commission merchant, who transmitted it to his correspondent 
on the Continent. Some months having elapsed thereafter, 
during which time its possessor had ascertained the true value 
of his purchase, the manufacturer was surprised at receiving 
numerous inquiries on the subject of this lump of glass, on the 
part of several English opticians. These were anxious to pro- 
cure portions of a material, the fame of which had reached 
them from abroad. Upon this, the maker instituted a search, 
and having succeeded in identifying some fragments, as having 
formed part of the same melting, was enabled to procure very 
considerable prices for that upon which he had previously set 
little or no value, and which had been preserved only through 
accident. 

On a yet more recent occasion, information having reached 
London that a large and superior object glass was on sale in 
the metropolis of a neighboring kingdom, one of our most cele- 
brated astronomers hastened across the channel, and while 
others were chaffering with its possessor about the price, our 
countryman stept in, and paying at once the full amount de- 
manded, brought off the prize, to the great mortification of his 
competitors. 



CHAP. XII. 



ON THE SPECIFIC GRAVITY OF GLASS. 

Importance of this duality.— Experiments of Loysel.— His Reasonings and 
Formulae. — Specific weight augmented by Lime. — Mixed Glasses. — Their 
Specific weight. — Method of Determining this.— Influence of Temperature 
on the Specific weight of Glass. 

The specific gravity of glass is a quality of considerable im- 
portance, when the material is required for conversion into the 
object-glasses of achromatic telescopes, or for the composition 
of counterfeit gems, although any very minute attention to this 
point is not considered essential in conducting the commoner 
processes of the glass-house. 

Loysel, to whose justly esteemed work on the art of glass- 
making allusion has been so frequently made in these pages, 
went through a series of experiments upon the specific gravi- 
ties of various vitreous bodies, with the view of giving such 
instructions for the composition of the nicer qualities of glass, 



CHAP. XII. SPECIFIC GRAVITY OF GLASS. 208 

as should absolve manufacturers from the necessity of making 
those preliminary trials upon every occasion, which are attended 
by much inconvenient delay in the prosecution of extensive 
operations* 

Adopting the practical aim of this French author, some of 
his ingenious formulae will be here given, together with a state- 
ment of the premises whereupon they were founded. 

The specific gravity of water being expressed by the num- 
ber 100, that of sand is 263; while soda deprived of all car- 
bonic acid by fusion in the furnace of a glass-house, is of the 
specific weight 199, and the same substance, when brought 
again by cooling to a concrete state, is not heavier than 222. 
It might, therefore, be supposed that the specific weight of 
glass, considered as a compound of sand and alkali, would be 
diminished in proportion as its dose of silica was lessened and 
that of its alkali was augmented. The contrary of this fact 
results, however, from the combination of these two substances 
through the agency of fire. 

" Sand," says M. Loysel, " contains, in addition to silica, 
some other substance, the nature of which has not been investi- 
gated, and which is sensibly disengaged from the silica by the 
alkali, in the form of an elastic fluid, in the act of their com- 
bination to form glass. 

" We are ignorant of the degree wherein caloric adheres 
more or less strongly to one or other of these substances ; in 
other words, their capacity for heat is not known ; but, in 
order to avoid errors, it will suffice, that we know the results 
of several similar combinations. If we ascertain carefully the 
doses of silica and alkali, which compose glasses formed of 
these substances at different degrees of heat, together with 
their various specific gravities, we perceive that the differences 
between their doses of alkali are obviously proportional to the 
differences of their weights. Knowing then how far these 
proportions vary in respect of two descriptions of glass, we 
have it in our power to compute, with respect to a third com- 
position, either its quantity of alkali from its specific gravity, 
or, on the other hand, its weight from its dose of alkali." 

From actual experiments made on different glasses, the fol- 
lowing results have been obtained, the weight of water being 
expressed by 100 : — 

Glass, No. 1. contained 80 parts silica, 20 parts alkali, its specific gravity 236 
No. 2 54 — silica, 46 — alkali, its specific gravity 254 

Difference - - - 26 18 

If it be then required to know what proportions of the same 
materials must be used for the production of another glass, 



204 GLASS MANUFACTURE. CHAP. XII. 

No. 3., the specific gravity of which will be 242, the solution 
of the question may be found by the following formulae : — As 
the difference between the specific weights of the compounds 1. 
and 2., which is 18, is to the difference between the weights 
of 1. and 3., which is 6 : so is the difference between the doses 
of alkali employed in Nos. 1. and 2., which is 26, to the differ- 
ence between the doses of Nos. 1. and 3., and which difference 
is thus found to be 9. Adding then this number to that which 
represents the alkali of No. 1., we may conclude that the glass 
of No. 3. must contain 29 parts of alkali and 71 parts of silica. 
It has been proved by experiment that glass of the specific 
gravity proposed, 242, is composed by the union of 70 of silica 
with 30 of alkali. 

When a manufacturer has thus two well-established results 
to serve as general means of comparison, the simple ascertain- 
ment of specific gravities will suffice for determining if any 
variation has taken place in the manufacture, as well as for 
discovering, and in general remedying, its cause. 

If any lime enters into its composition, as is the case with 
glass of common quality, its weight is rapidly augmented, and 
it is therefore useful to determine, from time to time, the 
weight of the glass produced, comparing it with that of some 
other sample which is known to have been well and carefully 
made. If it is seen that the weight increases, it may be con- 
cluded, either that a larger proportion than usual of lime is 
present, or that the fire has not been sufficienty urged, and that 
too large a proportion of alkali has been allowed to remain in 
combination with the glass. 

The rule already stated is said by M. Loysel to apply with 
equal certainty to the heavy glasses composed of silica and 
oxide of lead, the differences between the weights of various 
specimens of flint-gkss being also proportional to the differ- 
ences in their quantities of metallic oxide : — 

Glass, No. 1. composed of 27 sand 73 minium, has a specific gravity of 520 

No. 2. — 11 — 89 - — = — ■ 657 

Difference -.---- * - - - 16 137 

From these data, the specific gravity of another composition, 
No. 3.— -made up of 20 parts sand and 80 parts minium, may 
thus be ascertained :— -As the difference between the quantities 
of minium contained in Nos. 1. and 2. is to the difference be- 
tween the proportional quantities of minium in Nos. 1. and 3. ; 
so is the difference between the weights of 1. and 2. to the 
difference between the specific gravities of 1. and 3., and which 
is thus found to amount to 59 ; which number, the quantity of 



CHAP. XII. SPECIFIC GRAVITY OF GLASS. 205 

oxide being greater in No. 3., must be added to 520, the weight 
of No. 1., and we thus have 579 as the weight of the proposed 
composition. 

In forming flint glass, it is proper, in addition to the sand 
and minium above supposed, to employ alkaline substances ; 
and it is desirable that the manufacturer should have it in his 
power to predict, within a trifling amount, the specific weight 
of every compound that he may determine to employ. The 
means to be employed by him for the attainment of this end 
are founded on the following considerations : — 

The manufacture of flint glass requires the employment of a 
ower degree of heat than is necessary for the formation of 
other descriptions, which do not contain an equal abundance 
of fluxing materials for vitrifying the sand. The temperature 
of the furnace is commonly such, that if glass be made in it 
composed of silica and alkali in such proportions that the one 
will saturate the other, it will usually contain about 75 parts 
of silica, and 25 parts of alkali ; and this glass will have a spe- 
cific gravity of about 24. The same means of heating being 
employed, 73 parts of minium will be saturated by 27 parts of 
sand, producing glass the specific weight of which is 52. In 
practice, it is, however, probable, that 75 parts of minium will 
combine with 25 of sand, and the result will have the specific 
gravity of 54. 

On the other hand, if two glasses of different character, one 
of which is composed of silica and alkali, and the other of silica 
and lead, are melted together, the specific gravity of each being 
known, the weight of the compound resulting from their union 
will depart in only a very trifling degree from that which 
would be given by calculation, according to the usual rules for 
determining the specific gravities of alloys. The same result 
will equally ensue, if, instead of thus previously forming two 
"ifferent kinds of glass, the materials of which they should be 
omposed are themselves brought together for the purpose of 
heir original vitrification. 

If, then, we consider the sand of the composition as divided 
nto two portions, one of which must necessarily combine with 
he minium for its vitrification, while the other is required for 
he saturation of the alkali — the surplus quantity, if any, of the 
atter constituent being dissipated by heat during the process 
f vitrification, the calculation necessary for determining the 

eight of the compound will proceed according to the follow- 

g example: — 

Let it be supposed that the manufacturer wishes to form* flint 

lass by the union of 100 parts of sand, 50 parts of minium, 

nd 40 of potash. These materials might be divided into the 

S 



206 GLASS MANUFACTURE. CHAP. XII. 

following proportions for producing two very different descrip- 
tions of glass :— Thus, the 50 parts of minium, which would 
be reduced in the process of vitrification to 48 parts, would be 
completely vitrified by the addition of 16 parts of sand ; the ab- 
solute weight of glass thus formed would be 64, and its specific 
weight (that of water being 10) would, as before stated, be 54. 
The quantity of sand remaining (84 parts) might be combined 
with the whole of the potash ; but as, in the process of vitrifi- 
cation, all the surplus quantity of the alkali would be dissi- 
pated, glass would be formed containing 84 parts of sand and 28 
of potash, having 112 as its absolute, and 24 as its specific 
weight. If, then, the whole materials are placed together in 
the crucible for their original vitrification, we shall have, after 
the reduction of the minium by 2 parts, and the dissipation by 
heat of 12 parts of potash, a glass, the absolute weight of 
which is 176, and whereof we desire to know the specific 
gravity. For ascertaining this, the specific weights of the two 
kinds of glass that might be separately formed, must be multi- 
plied into each other, and their sum again multiplied by the ab- 
solute weight of both, in order to find a dividend. Proceeding, 
then, with the absolute weights of the two descriptions of 
glass which might be formed, and multiplying each separately, 
by the specific weight of the other, adding the two products 
together, another sum will be obtained, by employing which as 
a divisor, the quotient will be equal to the specific gravity of 
the compound. 

Thus, in the above example, the specific weights, 54 and 24, 
of the two descriptions, being multiplied into each other, and 
their sum multiplied by 176, the absolute weight of both, a 
product will be obtained of 228,096 for the dividend. Multi- 
plying, then, 64, the absolute weight of one glass, by 24, the 
specific weight of the other; and again, 112, the absolute 
weight of the remaining glass, by the remaining specific weight 
54, we have two sums, 1536 and 6048, which, added together, 
and employed as a divisor, gives, as its quotient, a very minute 
fraction over 30, which is known to be the specific gravity of 
glass composed of sand, minium, and potash, in the proportions 
first stated. 

With respect to heavy glasses, results are obtained by calcu- 
lation, which are rather greater than the reality ; a circum- 
stance for which it is not difficult to account. The great abun- 
dance of oxide of lead used in their composition, attacks the 
body of the crucible, so as partially to dissolve it ; and being 
thus provided with a somewhat larger proportion of the lighter 
material, the weight of the compound will be necessarily and 
proportionally diminished. This difference between the com- 



CHAP. XII. SPECIFIC GRAVITY OF GLASS. 207 

puted and the real weights will, of course, be greater, according 
as the proportion of minium is augmented ; its action upon the 
crucible being, by such means, rendered more destructive. 

Notwithstanding the degree of uncertainty thus occasioned, 
it must still be useful to know how, by a very simple calcula- 
tion, to make a near approximation to the truth, and thus, as 
already said, to avoid the necessity of conducting long and un- 
certain preliminary experiments. 

The specific gravity of glass is influenced by the degree of 
heat to which it has been exposed during its vitrification ; be- 
ing always least when the temperature has been greatest. The 
cause of this variation is to be found in the different quantities 
of alkali that have been dissipated, the silica appearing to de- 
part from the completeness of its aggregation, in proportion as 
it is deprived of alkali* 

Flint glass is not entitled to any drawback upon its exporta- 
tion, unless its specific gravity be at least three times that of 
water. The duty drawn back on the shipment of flint glass is 
considerably greater than the rate originally paid on other de- 
scriptions ; and but for the resort which is had to its gravity as 
a test, those other descriptions might in many cases be substi- 
tuted, and a considerable profit be thereby fraudulently obtain- 
ed by the exporter at the expense of the revenue. 

* The rule for ascertaining the mean specific gravity of different bodies 
should never be relied on until verified by experiment. The condensation of 
volume which some substances undergo when brought into combination 
with others, is such as to render all calculations concerning them, under 
such circumstances, vague and erroneous. From the experiments of M. 
Loysel it would appear, however, that except in the case which he 'has no- 
ticed, that of employing different degrees of heat, this condensation does not 
occur with the various compositions of which glass is formed, and recourse 
may therefore be had to the formula usually employed for ascertaining mean 
specific gravities, when we desire to determine those of different vitreous 
combinations. The rule is as follows : 

The specific gravity of one body is to that of another, as the weight of 
the first divided by its volume is to the weight of the second divided by its 
volume ; and the mean specific gravity of the two is found by dividing the 
sum of the weights by the sum of the volumes. 

Let W, w, be the two weights ; V, v, the two volumes ; P, p, the two spe- 
cific gravities ; and M, the calculated mean specific gravity. 

W-fzo W w Wjp-fwP 

Then, M == ; andV -(- v= 1 = ; hence 

y+v p p Vp 

W + w W + w (W-f-w)Pp 

— _ — M. 

V-fu Wp-J-teP Yw+pW 



208 GLASS MANUFACTURE. CHAP. XIII. 



CHAP. XIII. 
ON THE ART OF COLORING GLASS. 

Antiquity of this Art. — Specimens of Roman Mosaic. — Analysis of these 
by Klaproth — Metallic Oxides.— Gold-Purple.— Its great Coloring Power. 
— Kunckel. — His Proficiency in Coloring Glass. — Yellow Color— From Sil- 
ver — From Lead— From Tartar — From Beechwood Charcoal — From Oxide 
of Iron. — Green. — Black Glass. — Blue. — Directions found in old Authors. 
— Imitation of the Garnet— Of the Amethyst— Of the Emerald— Of Sap- 
phires. — Opaque Glasses — Black — White— Opal. — Ancient Pictures form- 
ed of Colored Glass — How executed. — Description of Ancient Mosaics. — 
More recent Prosecution of this Art. — Accidental Coloring of Plate Glass 
at St. Gobain. — Ineffectual Attempts to reproduce this Effect. 

It appears probable that the art of coloring glass was disco- 
vered and prosecuted at a period very little subsequent to that 
of the manufacture of the article itself. The most ancient au- 
thors who have mentioned the existence of the material, have 
also recorded the fact of its being tinged with various colors, 
in imitation of gems. Strabo, Seneca, and Pliny, all make 
mention of this use, as being one to which glass was applied 
by artists in very early times. 

The fact has already been mentioned of colored figures hav- 
ing been found with Egyptian mummies, and which are, there- 
fore, known to have been in existence for upwards of 3000 
years. These curious relics of ancient times have also been 
discovered decorated with colored glass beads ; and a mummy 
thus ornamented is to be seen in the British Museum. 

In the reign of Augustus, the Romans began the use of co- 
lored glass in the composition of mosaic decorations. Several 
specimens of tins kind have been found at a late period, among 
the ruins of a villa built by Tiberius in the island of Capri ; 
and some of these specimens having been subjected to analysis 
by the accurate and ingenious. Klaproth, it is known that in 
that early time recourse was had to the same class of coloring 
ingredients as is employed by the moderns. Some difference 
must, indeed, have been observed in their processes, as the an- 
cients were unacquainted with the use of the mineral acids, 
which are now found to be so convenient in the preparation of 
metallic oxides. 

Klaproth has given the following as the result of his exami- 
nation of some of the Roman specimens above mentioned : — 

One which was a lively copper red, opaque, and very bright 
where recently fractured, contained, in 200 grains, — 



CHAP. XIII. COLORING OF GLASS. 209 

Silex 142 

Oxide of lead 28 

copper 15 

iron 2 

Alumine 5 

Lime 3 

195 

Another, a light verdigris green, also opaque, with a splendent 
fracture and scoriaceous, contained in a similar quantity, — 

Silex 130 

Oxide of copper 20 

lead 15 

iron 7 

Lime 13 

Alumine* 11 

196 

It is remarkable that the constituent ingredients of both these 
specimens should prove to be the same. The difference be- 
tween them exists only in their relative proportions ; and the 
colors depend upon the different degrees of oxidation of the 
copper. Sub-oxide of copper, — that is, copper which has com- 
bined with itself only half the quantity of oxygen required for 
the production of the perfect oxide — produces a red enamel ; 
while that which has received its full proportion of oxygen 
yields a green enamel color. 

The specimen of ancient blue glass which was analyzed by 
Klaproth contained, — 

Silex 163 parts. 

Oxide of iron 19 

copper 1 

Alumine 3 

Lime 0^ 

It appears, therefore, to have been indebted to the oxide of iron 
for its blue color, as no trace was detected of any other ingre- 
dient to which this could be referred. Since the discovery of 
he certain and commodious method of producing blue enamel 
>y means of cobalt, the art of obtaining this color from iron has 
been lost. 

S2 



210 GLASS MANUFACTURE. CHAP. XIII. 

The causes which influence the employment of metallic ox- 
ides for the embellishment of porcelain have been sufficiently 
detailed in the preceding treatise. The same reasons also 
oblige the artist to have recourse to the same class of sub- 
stances for imparting colors to glass. The mode of application 
of coloring materials to these two branches of manufacture dif- 
fers, however, in this, — that while, in ornamenting porcelain, 
they are applied superficially, in the manner of pigments, they 
enter more intimately into the composition of glass, being 
transfused through the whole mass, and equally incorporated 
with its entire substance. 

The preparation of metallic oxides as coloring materials is 
nearly similar in all cases ; it will not, therefore, be necessary 
here to repeat directions, or to give many explanations upon 
that head. 

Gold, in a state of great division and oxidated, has long been 
celebrated as a means for imparting to glass a most exquisite 
purple-red color resembling the ruby, and nearly equalling that 
gem in the richness of its hue. It is not by any means easy to 
prepare glass of this color with any certamty of a successful 
result. The great tendency which is shown by gold to assume 
the reguline state, when exposed to excessive heat, to carbona- 
ceous vapors, or to the action of hydrogen, renders necessary a 
great degree of careful management in the various processes. 

The manner has already been given of preparing the purple 
precipitate of Cassius ; the form wherein gold has been used 
with so much celebrity in imparting red and purple colors. It 
has been very generally imagined, that the tin used in the pre- 
paration of this precipitate is essential to the production of the 
requisite color ; an opinion which has been shown to be void of 
foundation, as preparations of gold have been made without the 
agency of tin, and which have equally possessed the power of 
imparting the finest purple color to glass. The coloring proper- 
ty of any of the simple oxides of gold is found to be mate- 
rially greater than that of Cassius's precipitate ; which circum- 
stance has been brought forward as another argument to prove 
that the presence of tin is far from adding any thing to the 
body of the color. It is probable, however, that, although not 
indispensable, tin is yet useful, as enabling the gold to bear 
without reduction a higher degree and a longer continuance of 
heat. With this same object, it has been recommended to add 
to the precipitate, before using it, a small quantity of nitre, by 
which the gold will be preserved at its due degree of oxidation. 

It is not essential that gold used for this preparation should 
be absolutely pure or unalloyed ; since neither copper nor sil- 



€HAP. XIII. COLORING OF GLASS. 211 

ver, when present in small quantities, appears to alter or di- 
minish its coloring power. 

Fulminating gold, prepared by precipitating the metal from 
its nitro-muriatic solution by means of ammonia, is also used in 
coloring glass ; but as this preparation would explode violently 
when exposed to a heat even very much below that to which 
it must be subjected in use, this explosive property must be 
previously removed by mixing it with a fixed alkali, and re- 
taining it for some time at a comparatively low temperature. 
A.more manageable preparation results from the precipitation 
of the nitro-muriate of gold by means of carbonate of potash. 
This is not fulminating, as it is from the presence of ammonia 
that the explosive property is derived. 

A very ingenious process has been used for producing an in- 
timate union -between the oxide of gold and silex. This con- 
sists of adding to the solution of the metal in nitro-muriatic 
acid, a proportion of silica dissolved in an alkaline lixivium, 
and pouring therein any acid in sufficient quantity to saturate 
the alkali. In this case, the silex and gold are precipitated in 
very intimate combination; and if then washed with clear 
water, dried, and mixed with nitre, borax, or any other suitable 
fluxing substance, will be fit for use as a coloring material. 

When the precipitate of Cassius is employed, about one 
sixth part of its weight is added of perfect white oxide of anti- 
mony. This, from imparting a yellowish tinge, is considered 
to be an important ingredient in fine ruby-colored glass. 

The proper management of the heat employed in the pro- 
duction of this much-admired preparation is a difficult acquire- 
ment, known only to clever and experienced artists. If the 
temperature be allowed to rise too high, the color will be much 
injured, and probably even altogether destroyed. The contact 
of every kind of smoke and vapor should also be carefully 
avoided in the fusion of ruby-colored glass, which is said to be 
apparently colorless when it leaves the crucible, and. only to 
put on its exquisite tint as it becomes cool. 

Kunckel and other old writers upon the art of manufacturing 
glass have stated, that the coloring powers of the purple pre- 
cipitate of. Cassius are so considerable, as that one part, if added 
to one thousand parts of glass, will impart to the whole a full 
and rich body of color. 

The artist just mentioned, who was greatly celebrated for 
his attainments in this ornamental branch of the art, was in 
oonsequence ennobled by Charles XL king of Sweden, and as- 
sumed the name of Lowenstiern. He made artificial rubies, 
which were highly esteemed, and which he sold, in the man- 
ner of real gems, according to their weight, and at very consid- 



212 GLASS MANUFACTURE. CHAP. XIII. 

erable prices. The achievement upon which he most prided 
himself, was the production of a cup of ruby glass, which was 
of the thickness of an inch, and weighed twenty-four pounds : 
this cup went into the possession of the elector of Cologne. 

Kunckel directed, in 1679, the operations of the glass-houses 
at Potsdam, where he met with the greatest encouragement, 
and was liberally assisted in his researches by the elector of 
Brandenburg, who expended the sum of 1600 ducats to assist 
the efforts of the artist towards attaining perfection in the art 
of making ruby glass. A cup, with a cover of this material, 
which was made by him, and is still in existence at Berlin, 
continues to be an object of much admiration. 

Silver, in all its forms of oxidation, imparts a very pure and 
beautiful yellow color to vitreous bodies; but this color is easi- 
ly destroyed, through the accidental employment of too high a 
decree of heat: an evil against the occurrence of which it is so 
exceedingly difficult to provide, that silver is very seldom re- 
sorted to as a coloring material by glass-workers. The incon- j 
venience here mentioned may in some degree be avoided 
when oxides of silver are used in combination with alumine, as 
in the ornamenting of porcelain ; but this remedy is manifestly 
inapplicable to glass. Other bodies can, however, be used with 
the best effect in imparting a yellow color to this substance. 

Oxide of lead employed alone, if in very considerable quanti- 
ty, would give a very good yellow color ; but as it would re- 
quire that at least three fourths of the weight of the glass 
should be made up of this oxide, in order to give sufficient in- 
tensity to the color, it is very seldom used for the purpose. 
Glass thus formed would be inconveniently soft, and from its 
powerful fluxing quality would act injuriously upon the cruci- 
bles in which it was made. 

Chromate of lead, which is not liable to the objections just 
mentioned, is on that account used preferably. Before the com- 
paratively recent discoveries in chemical science had shown to 
artists in what manner to procure this valuable coloring ingre- 
dient with sufficient facility and at a moderate cost, the makers 
of colored glass employed the oxides of lead, silver, and anti- 
mony in combination, for the production of yellow colors ; vary- 
ing the proportions wherein each substance was used according 
to the hue which it was desired to impart. 

Colors varying in their shades from brown to a fine transpa- 
rent yellow may be given to common glass by simply adding to 
it, while in a state of perfect fusion, some vegetable carbonace- 
ous matter. This must always be supplied in excess, since 
part of it, rising to the top of the crucible, will be burnt away; 
but some portion will also continue uniformly diffused through- 



CHAP. XIH. COLORING OF GLASS. 213 

out the glass, and, without at all impairing its transparent qual- 
ity, will give to it a very fine yellow. The substance which 
most commonly has been employed for this purpose is tartar ; 
but almost any solid and inflammable vegetable matter will 
probably answer equally well. Charcoal made from beech wood 
is found to be altogether efficacious. The addition of a small 
quantity of nitre is sometimes useful in clearing the color and 
removing any cloudiness which it may have contracted ; but if 
great discretion be not shown in the addition of this substance, 
the color will be altogether destroyed. During the time of its 
preparation, the glass swells very much in the crucible, owing 
to the escape of part of the carbonaceous matter in the form of 
gas ; and when tartar is employed, this effect is experienced in 
an exaggerated degree. It is said that this effervescence might 
be avoided, if freshly burnt and perfectly dried charcoal were 
heated strongly in a close vessel, and added in that state to the 
contents of the crucible. 

The oxides of iron give many and very different shades of 
enamel colors. It has already been mentioned, that the green 
eolor of common bottle-glass is owing to the presence of iron 
in the unpurified sea-sand and ashes of which it is composed. 
An increased quantity of this oxide, if applied to glass when in 
a state of perfect vitrification, will give a yellow color to the 
mass. A still larger quantity will impart a brownish black hue, 
which, however, appears to be nothing more than a yellow very 
lighly concentrated, as the latter color may be again produced 
by simply diluting the contents of the crucible with an addi- 
tional quantity of uncolored glass. 

The red color which is imparted by the oxides of iron to por- 
celain, is owing to its state of imperfect vitrification, whereby 
the metal is held suspended in a state of minute division 
throughout the mass, which same effect is indeed apparent in 
the treatment of glass up to a certain point ; but when in the 
advancing stages of vitrification the heat is raised so that a per- 
fect fusion of the glassy substance as well as of the oxide is 
produced, the color is immediately converted to yellow. 

The use of the black oxide of manganese in correcting the 
impurities of the alkali employed in the original composition of 
glass, as well as in removing the green tinge resulting from 
the presence of iron in the sand, has already been explained. 
Where these imperfections do not exist in the original ingre- 
dients, if manganese be added to the glass, it will impart a pur- 
lish red color. This oxide also forms a principal constituent 
in the production of black glasses : it is most commonly used in 
ombination with nitre. If any portion of arsenical salts should 
be present in the glass, it is altogether useless to attempt the 



214 GLASS MANUFACTURE. CHAP. XIII. 

employment of manganese as a coloring ingredient, since its 
efficacy would be wholly destroyed. 

All the simple as well as the carbonated oxides of copper, 
when perfectly vitrified in conjunction with any kind of glass 
or fluxing material, will yield a very fine green, and the chan- 
ces of complete success in the attainment of this are greater 
than attend the production of most other colors. It appears to 
be nearly a matter of indifference which of the combinations of 
copper with oxygen are employed for the purpose. The pre- 
parations most usually chosen are either the carbonated oxide 
resulting from the addition of sulphate of copper to some car- 
bonated alkali, or that which is known as the ces ustum, which 
is copper oxidated and calcined simply by means of heat and 
the access of air. 

Copper may be made to yield a carmine red color, and if mix- 
ed with iron, a full deep red, by adding to the glass with which 
it has already been combined a quantity of tartar. This addi- 
tion must not be made until the glass is in a state of perfect fu- 
sion, and the mixture should be worked off without delay. It 
should be mentioned that when used for the production of these 
colors, the oxide of copper must be reduced to nearly the regu- 
line state. If the heat is continued long after the tartar has 
been added, the effect will be lost, and the green color re- 
stored. 

When the oxides of copper and iron are thus united for de- 
veloping a full deep red color, the iron must be to the copper 
in the proportion of three parts to one ; and according as this 
proportionate difference is lessened, so will the color be found 
to approach to the carmine tint. 

The time for stirring in the tartar should be chosen when 
the melted glass appears of a faint greenish yellow ; the whole 
mass will then immediately swell up. prodigiously ; and upon 
again subsiding will appear, as before stated, of a clear red co- 
lor, and fit for being immediately used. It is probable that char- 
coal or other carbonaceous matters might be substituted for tar- 
tar in this process with equal success. 

Copper in a state of oxidation is often used when combined 
with the oxides of manganese and iron for the production of 
black glass. 

The protoxide of chromium may be used for producing a 
green color in glass, with as much advantage as attends its em- 
ployment in the embellishment of porcelain, that substance be- 
ing capable of sustaining without injury the highest heat of the 
crucible. Chrome is the natural coloring matter of the precious 
emerald, and is found to be a very valuable substance in the 
composition of artificial gems. 



CHAP. XIII. COLORING OF O^LASS. 215 

Oxide of cobalt is universally employed for the production of 
blue colors in vitrifiable bodies. The fine deep shade which it 
imparts is unalterable by fire of any degree of intensity, and suc- 
ceeds equally well with every different composition of glass. 

This metallic oxide is also employed towards the composition 
of other colors : combined with the oxides of lead and antimony, 
it furnishes a green ; and if mixed with those of manganese and 
iron, produces a very fine black. 

Neri, Kunckel, and Fontanieu have left in their writings 
many recipes for the preparation of artificial gems through the 
mployment of different coloring materials. The directions, as 
iven in the works of these authors, differ so importantly the one 
from the other as regards the proportions best fitted for the 
omposition of the same article, that we are forced to believe 
ither that some great errors have been committed on the part 
f their subsequent editors, or that the writers themselves were 
wanting in the kind and degree of knowledge to which they 
pretended, and which were required to fit them for the task 
hey undertook. 

A few of these recipes, and such as appear most free from 
his objection, may be here given. 

The basis of each of these compositions is most frequently 
jither one of the colorless glasses or pastes described in Chap- 
er VII. , or some other very similar vitreous compound ; but it 
sometimes happens that the constituent materials of the glass, 
und the proportions wherein they are to be brought together, 
ire indicated as well as the coloring substances. 

The following is recommended by Neri, as furnishing a very 
excellent imitation of the garnet : — Rock crystal 2 ounces, min- 
um 6 ounces, manganese 16 grains, zaffre 2 grains. This must 
>e a very inconvenient composition, both on account of the ex- 
ceeding softness of the glass, and the destructive effect it would 
lave upon the crucible during the time of its preparation. We 
earn from the analysis of Berzelius, that the coloring matter 
)f the " precious garnet," that being the variety which it is 
wished thus to imitate, consists of the black oxide of iron and 
)xide of manganese. A more modern recipe than the fore- 
going for the successful imitation of this gem, consists of purest 
vhite glass 2 ounces, glass of antimony 1 ounce, Cassius's pre- 
cipitate 1 grain, oxide of manganese 1 grain ; which composi- 
tion is free from the objections to which that of Neri is so justly 
exposed. 

The directions of Fontanieu for imitating the color of the 
methyst are, that to 24 ounces of the glass composed according 
:o instructions given in Chap. VII. under the number 5, are to 
e added half an ounce of the oxide of manganese, 4 grains of 



216 MANUFACTURE OF GLASS. CHAP. XIII. 

the purple precipitate of gold, and l^oz. of nitre, but it is im- 
possible to believe that the recipe of JFontanieu has been cor- 
rectly given. The quantity of coloring matter here indicated 
would be better proportioned to 24 pounds of glass, than to the 
same number of ounces as directed. 

Many, and greatly varying instructions have been given for 
imitating the emerald. Fontanieu recommends 160 parts of 
any glass basis which contains a large proportion of lead, 4 parts 
of oxide of copper prepared by simple calcination, and T \th of a 
part of any oxide of iron ; which last ingredient is added for 
the purpose of giving something like a richness of tint, and for 
correcting the coldness of hue that would result from the em- 
ployment of the oxide of copper alone. The presence of lead in 
the glass would also conduce to the same end. 

Another rule given from the same authority directs the use 
of 576 parts of glass, similarly constituted to that pointed out in 
the last receipt, 6 parts of the same oxide of copper, and only 
Y^th of a part of oxide of iron; thus differing from the former 
compound, only as to the proportions wherein the coloring in- 
gredients are employed. 

A third receipt for the attainment of the same object is very 
different from the two preceding. It recommends the employ- 
ment of 200 parts of fine sand, 400 parts of minium, 8 of cal- 
cined verdigris, and as much as 1 part of oxide of iron. A fourth 
method for the composition of glass of an emerald green is, to 
mix, in due proportions, some blue glass colored by means 
of oxide of cobalt, with yellow glass prepared with oxide of an- 
timony. A great many other prescriptions are offered for the 
imitations of emeralds, but these vary more in the relative pro- 
portions of their ingredients than in the principle of their com- 
position ; and it cannot, therefore, be necessary to insert them 
here. 

The imitation of sapphires is always effected through the 
coloring agency of the oxides of cobalt and manganese. There 
is, however, a material difference as regards the basis of the 
glass in the various directions which are found for the purpose ; 
one recommending that this shall be composed without lead, 
and another directing that this mineral shall enter largely into 
the composition of the paste. To 100 parts of glass of the first 
kind it is directed that 1 part of zaifre, and y^th of a' part of ox- 
ide of manganese, shall be added. Where the second descrip- 
tion of paste is recommended as the basis, the artist is directed 
to prepare this by adding to 240 parts of glass frit made with 
only soda and silica, 192 parts of minium, 2 of zaffre, and |d of 
a part of manganese. This compound must be fused together, 



CHAP. XIII. COLORING OF GLASS. 217 

poured into water, and then remelted as directed by Fontanieu, 
for the formation of the pastes described in Chapter VII. 

The oxide of cobalt is, in the present day, a necessary ingre- 
dient in every imitation of the sapphire, so that it is never at- 
tempted to act without it. We have seen, however, that a 
very fine blue glass was formerly made having the oxide of iron 
for its coloring ingredient, and as it is known that the coloring 
property of real gems having that hue, resides in this metal 
when in some particular state of oxidation, we must own to 
having lost, in this respect, one means of imitating nature which 
was known and exercised by our predecessors. 

The colored glasses comprised in the foregoing descriptions, 
are all translucent. The preparation of others, which have the 
opposite quality of opacity, is effected either by means of apply- 
ing excessive doses of the same metallic oxides which, in small- 
er quantities, are used for imparting colors ; or by the addition 
to those oxides of some other substance which has the property 
of obstructing the rays of light in their passage through the 
^lass. 

In general, the first method is used only for the production 
of black glass, while the second plan is pursued with all other 
descriptions, as well those which are designed to retain a per- 
manent white color, as with yellow, blue, green, or any other 
colored opaque glasses. 

The most approved method of preparing black glass, of good 
quality, which shall be of a full deep black and perfectly opaque, 
is by mixing together equal parts of black oxide of manganese, 
zaffre, and protoxide of iron ; adding one part of this mixture to 
fifteen or twenty parts of colorless transparent glass, and fusing 
the whole together. 

Some large and beautiful slabs of perfectly black glass have 
lately been imported into London from St. Petersburgh, and ap- 
pear well fitted to be used as substitutes for marble in the con- 
struction of certain articles of household furniture. 

White opaque glass, which has this quality imparted to it by 
means of the oxide of tin, is called enamel ; and it is this sub- 
stance of which the dial-plates of watches and of table clocks 
are commonly made. This compound is, however, too expen- 
sive for more ordinary uses, and a very good white glass is made 
or such purposes by substituting for the oxide of tin, a consid- 
erable proportion of phosphate of lime in the state of a very fine 
powder. This substance is procurable in great abundance, and 
t v a moderate cost, in almost every situation. Phosphate of lime 
is extremely infusible, so that the opaqueness of the glass with 
which it is united, arises from its holding in intimate mixture 
an unvitrescible earthy salt. 

T 



218 GLASS MANUFACTURE. CHAP. XIII. 

One receipt given by Neri for producing white opaque glass 
is as follows : — Mix together 60 parts of fine white sand, and 40 
parts of potash, with 10 of finely pounded bone-ash, and melt 
the compound during the same length of time as is usually em- 
ployed in ordinary glass-making. It is said that this glass is 
transparent for as long as it continues at a full red heat ; and 
that, as it gradually cools, it first puts on a milky appearance, 
and afterwards becomes wholly opaque. If this change does in 
reality take place, and is not rather the result of a deception 
which prevents the proper distinguishing of its degree of opacity 
while red-hot, it may probably arise from the circumstance that 
the excessive heat of the melted glass enables it to take up a 
greater quantity — in other words — to supersaturate itself with 
the phosphate of lime, which it parts with again in cooling. 

Another receipt of the same artist is 130 parts of calcined 
flint or fine sand, 70 parts of nitre, 12 of borax, 12 of tartrate of 
potash, 5 of arsenic, and 15 of bone-ash. 

Fontanieu has given directions for imitating the peculiar 
lustre of the semi-transparent opal, by mixing 576 parts of his 
glass No. 3. (Chap. VII.,) with 10 parts of muriate of silver, 2 
parts of magnetic iron ore, and 26 parts of bone-ash. The 
beautiful play of colors exhibited by the " precious opal " is de- 
servedly an object of much admiration, and it has always been 
a subject of interest to imitate successfully so pleasing an effect. 
Ornamental pieces of opal glass have usually been obtained 
from France ; but their production, of a quality fully equal to 
these importations, may n^w be witnessed in the London glass- 
works. 

The peculiar delicacy and beauty of this glass do not appear 
while it remains in a state of fusion or at a red heat, and are 
not fully developed until it is sufficiently cooled to have acquir- 
ed its quality of brittleness. 

Other colored glasses which are opaque, are made by the 
same processes as are followed with transparent glasses of the 
like colors, substituting for the common vitreous base, one of the 
above described, opaque-white glasses. 

The ancients employed methods of converting colored glasses 
into representations of natural objects, which were extremely 
beautiful, and the manner of producing which is now lost. The 
existence even of this art is only known in these modern days 
from specimens which have been accidentally discovered ; and 
our knowledge of the peculiar nature of their formation is 
wholly derived from the examination to which these specimens 
have been subjected. 

The fkst mention made of these works of art is to be found 



CHAP. XIII* COLORING OF GLASS. 219 

in the " Collection of Antiquities," by count Caylus, who de- 
scribed them as composed of delicate different-colored fibres of 
glass joined with the greatest nicety, and conglutinated into a 
compact homogeneous mass by fusion. Winkelmann, in his 
" Annotations on the History of the Arts among the Ancients," 
describes these same specimens as pictures made of glass tubes, 
and introduces them to further observation by these words : — 

The works of the ancients in glass which are not noticed in 
the history of the arts, deserve particularly to be mentioned in 
this place, more especially because the ancients carried the art 
of working in glass to a much higher degree than we have ar- 
rived at ; a fact which, to those who have not seen their works 
of this kind, might have the appearance of a groundless asser- 
tion." 

The author just quoted particularly describes two small 
pieces of glass thus constructed which were brought to Rome 
in the year 1765, and which, indeed, appear to have been well 
deserving of his careful examination, as confirming the opinion 
he had given respecting the superior proficiency of the an- 
cients. The account of these curiosities cannot be better given 
than in Winkelmann's own words : — " Each of them is not 
quite one inch long, and one third of an inch broad. One plate 
exhibits, on a dark ground of variegated colors, a bird repre- 
senting a duck of various very lively colors, more suitable to 
the Chinese arbitrary taste, than adapted to show the true tints 
of nature. The outlines are well decided and sharp ; the colors 
beautiful and pure, and have a very striking and brilliant effect, 
because the artist, according to the nature of the parts, has in 
some employed an opaque and in others a transparent glass. 
The most delicate pencil of the miniature painter could not 
have traced more accurately and distinctly either the circle of 
the pupil of the eye, or the apparently scaly feathers on the 
breast and wings, behind the beginning of which this piece had 
been broken. But the admiration of the beholder is at the high- 
est pitch when, by turning the glass, he sees the same bird on 
the reverse, without perceiving any difference in the smallest 
points ; whence we could not but conclude that this picture is 
continued through the whole thickness of the specimen, and 
that if the glass were cut transversely, the same picture of the 
duck would be found repeated in the several slabs ; a conclu- 
sion which was still further confirmed by the transparent places 
of some beautiful colors upon the eye and breast that were ob- 
served. The painting has on both sides a granular appearance, 
and seems to have been formed in the manner of mosaic works, 
x)f single pieces, but so accurately united, that a powerful mag- 
nify ing-glass was unable to discover any junctures. This cir- 



220 GLASS MANUFACTURE. CHAP. XIII. 

cumstance, and the continuation of the picture throughout the 
whole substance, rendered it extremely difficult to form any 
direct notion of the process or manner of forming such a work ; 
and the conception of it might have long continued enigmatical, 
were it not that, in the section of the fracture mentioned, lines 
are observable of the same colors which appear on the upper 
surface that pervade the whole mass from one side to the other ; 
whence it became a rational conclusion, that this kind of paint- 
ing must have been executed by joining variously colored fila- 
ments of glass, and subsequently fusing the same into one co- 
herent body. The other specimen is of almost th. ' i &me size, 
and made in the same manner. It exhibits ornamental draw- 
ings of green, white, and yellow colors, which are traced on a 
blue ground, and represent volutes, beads, and flowers, resting 
on pyramidally converging lines. All these are very distinct 
and separate, but so extremely small, that even a keen eye 
finds it difficult to perceive the subtle endings ; those, in par- 
ticular, in which the volutes terminate ; notwithstanding which, 
these ornaments pass uninterruptedly through the whole thick- 
ness of the piece." 

Klaproth, who had in his possession some specimens of these 
antique compositions in colored glass, compiled a paper upon the 
subject, which was read before the Royal Academy of Sciences 
at Berlin, in October, 1798 ; and the collection of antiquities 
formed by Mr. Townley, comprised a ring which contained a 
singular antique glass paste, which represented a bird of so 
small a delineation, as not to be distinctly visible without the 
aid of a magnifying lens, and which yet had every appearance 
of having been produced in the manner described by Winkel- 
mann. Numerous antique specimens, similarly composed, are 
deposited in the British Museum. They are for the most part 
fragments, and it is to be regretted that we are without any 
records of their origin. 

Keysler, the account of whose travels to different parts of 
Europe in the early part of the last century contains a great 
variety of entertaining and instructive matter, has given the 
following description of a mode of composing pictures in col- 
ored glass, which was at that time employed in decorating some 
of the churches in Rome. It will be seen that the method pur- 
sued by the Roman artists in some respects resembled that used 
for the composition of antique pastes, as described by Winkel- 
mann. Recourse appears to have been had to this mode of pro- 
ducing pictures, in cases where the original paintings on wood 
or canvas were perishing through the dampness of the walls, 
and where it was wished to supply their places with copies 
composed of an imperishable substance. 



CHAP. XIII. ROMAN MOSAICS. 221 

" The materials used are little pieces of glass, of all the dif- 
ferent shades in every tint or color like those of the fine Eng- 
lish worsted used in needle-work. The glass is first cast into 
thin cakes, which are afterwards cut into long pieces of differ- 
ent thickness. Many of the pieces used in the works on roofs 
and ceilings, which are, consequently, seen only at a great dis- 
tance, appear to be a finger's breadth ; but the finer works con- 
sist only of glass pins, if I may call them so, not thicker than 
a common sewing-needle, so that a portrait of four feet square 
shall take up two millions of such pins or studs. These are so 
closely joined together, that, after the piece is polished, it can 
hardly be discerned to be glass, but rather looks like a picture 
painted with the finest colors. The ground on which these 
vitreous pieces are inlaid is a paste compounded of calcined 
marble, fine sand, gum tragacanth, white of eggs, and oil : it is 
at first so soft that the pieces are easily inserted, and upon any 
oversight may be taken out again, and the paste new moulded 
for the admission of other pins ; but by degrees it grows as hard 
as a stone, so that no impression can be made on the work. 

" This paste is spread within a wooden frame, which for the 
larger pieces must not be less than a foot in breadth and thick- 
ness. A piece of about eighty square feet, if performed with 
tolerable care and delicacy, will employ eight artists for two 
years. 

" The pins of the several colors lie ready before the artists 
in cases, as the letters are laid before the compositors in u 
printing-house ; and such is their accuracy in imitating the 
finest strokes of the pencil, that the only apparent difference 
betwixt the original painting and such a copy is, that the latter 
has a much finer lustre, and the colors are more vivid. 5 ' 

An accident occurred many years ago in the plate-glass 
works at St. Gobain, which seemed to offer the means of ob- 
taining a bright red color for glass by the employment of cop- 
per, at a much less expense than has hitherto attended the pro- 
duction of that tint from gold. 

It will be remembered that, in the manufacture of platt 
glass, when the refining is completed, and it is wished to trans- 
fer a portion of its contents from the melting-pot to the cu- 
vette, a copper ladle js employed. It is necessary, while using 
this implement, to dip it occasionally into water, lest it should 
become too hot and warp, or possibly melt. On the occasion 
referred to, the workman having omitted, this necessary pre- 
caution, the last of these misfortunes ensued ; dipping the 
heated ladle once too often in the melted glass, only part was 
brought out attached to its iron handle. 

It was imagined that the copper thus melted would sink, by 

T2 



222 GLASS MANUFACTURE. CHAP. XIII. 

reason of its greater gravity, to the bottom, and would be found 
there in the metallic state on the emptying of the pot. The 
casting and annealing of the plates were proceeded with ac- 
cordingly ; and, on their completion, the workmen were sur- 
prised to find that not only were grains of metallic copper em- 
bedded in the substance of the glass, but bands uniformly col- 
ored of a fine bright red were distributed throughout the plates. 

The color must, in this case, have been produced by the cop- 
per, which was suddenly carried to the degree of oxidation 
necessary for its development. M. Guyton-Morveau, when in- 
formed of this circumstance, was desirous of ascertaining, by 
direct experiment, what means would be most efficacious in 
producing the same effect. The result of his endeavors has 
been published.* 

The first attempt was made with plate glass. In order to 
bring the glass and copper into more intimate union, the first 
was reduced to powder, and the other was used in the form of 
filings. The metal was used in the proportion of 3 parts to 
100 parts of glass : this mixture was brought to a state of com- 
plete fusion before the glass was poured out. No success at- 
tended this experiment, the glass appearing uncolored, and the 
copper remaining mixed with it mechanically in the form of 
metallic globules. 

The next trial was made with common white glass, mixed 
with twice the proportional weight of copper filings that had 
been employed in the first experiment. The compound having 
been completely melted, was found to have assumed a red color, 
which was uniformly diffused throughout the mass ; but this 
color was so deep as to render the glass nearly opaque. 

A trial made with copper, already in the form of an oxide, 
imparted a greenish color to the glass. 

It is impossible not to remark that the circumstances under 
which these experiments were conducted, as detailed by M. 
Guyton-Morveau, differ in some essential particulars from those 
which accompanied the accident by which they were suggested. 
In that case, the glass was already in the state of fusion, and 
probably also in a high state of incandescence, before the addi- 
tion of the copper. The proportion of metal used in the second 
experiment was evidently excessive ; and it is surprising that 
the effect produced did not lead M. Guyton-Morveau to try the 
effect of a smaller proportion. " - 

Attempts have been made to color glass by subjecting it to 
the action of heat, while surrounded by some cementing sub- 
stances already impregnated with metallic oxides as coloring in- 

*An. de Chim. vol. lxxiii. p. 132. 



CHAP. XIII. COLORING OF GLASS. 223 

gredients. In most of these cases the glass remained perfectly 
colorless, unless the heat had been carried sufficiently far to in- 
duce devitrification; which state, as it renders the material 
opaque, furnishes sufficient objection to the use of this method 
of coloring. Even in those cases where transparency is not re- 
quired, the same effect can be attained by easier means, and 
Tee from a very serious inconvenience, that of the adhesion 
of the cementing substance to the glass. Some curious facts 
connected with this subject will be detailed in the concluding 
chapter of this volume, which treats of the devitrification of 
glass. 



CHAP. XIV. 

ON THE ART OF STAINING AND PAINTING GLASS. 

This Art more recent than that of Coloring.— Encouraged by the Monks.— 
Early Specimen at St. Denis.— Art never much cultivated in England.— 
Splendid Paintings at Gouda — Directions given by old Authors for com* 
posing Colors.— Fluxes.— Vehicles for diluting Colors.— Description of va- 
rious Stains.— Method of floating these.— Of painting on Glass.— Imitation 
of ground Glass with transparent Patterns.— Description of Kiln employed. 
—Method of firing.— Second and third firing. — Ancient method of fixing 
different colored Glasses on each other. • 

The invention of the art of painting on and staining glass, 
although probably recent as compared with that of coloring the 
xxly of the metal when in fusion, is yet known to have existed 
or many centuries.' 

The exact period of its adoption is, indeed, involved in much 
obscurity ; and it can, at best, be regarded as only a reasonable 
conjecture, which assigns its principal excellence, if not its ori- 
gin, to the fostering care of those religious communities which, 
upon the breaking up of the great western empire of Rome, 
became, and for so long a period thereafter continued, the sole 
depositaries of learning and the arts in Europe. 

Endowed by the piety or superstition of their unenlightened 
followers with revenues far beyond their personal wants, the 
lergy of that time expended a portion of their superfluous wealth 
in the construction of those splendid temples which attest to the 
present day the architectural skill and genius of their founders, 
e: ining unsurpassed and almost unrivalled in their kind as 
bjects of admiration through a great portion of Europe. The 
misters of a religion which addressed itself to the imagina- 
ions and the feelings of its votaries, they could not, perhaps, 
Lave adopted more effectual means for obtaining and perpetu- 
itinp; their influence over the multitude. Some idea of the ex- 



224 GLASS MANUFACTURE. CHAP. XIV. 

tent to which these means must have operated may be formed 
by every one who recalls to mind the sensations of solemnity 
amounting to awe wherewith he has himself been struck as he 
has stood beneath the lofty sculptured arches of a cathedral, or 
walked through its lengthened aisles, radiant with tints glow- 
ing through emblazoned windows. 

The earliest specimens of these embellishments differ from 
those of more recent date in having been formed of small pieces 
of glass colored throughout during the process of its origina 
manufacture, and which, to distinguish it from glass colored or 
stained by the methods that will be hereafter described, has 
been called by artists pot metal. Pieces of this, cut to the shapes 
required, were joined together in the manner of mosaic by the 
interposition of lead, in a way which has since fallen greatly 
into disuse ; the method of staining and burning in metallic 
colors on the surface of the glass having been found far more 
beautiful, admitting of greater variety of tints, as well as of 
those delicate shadings which were manifestly unattainable by 
even the most laborious composition in mosaic work. 

Perhaps the oldest existing specimen of this later-discovered 
art of painting on glass is to be seen on the windows of the ab- 
bey of St. Denis, whereon were recorded, in 1194, various 
events which occurred during the first crusade. 

This art has never flourished to any great degree in England, 
where at no time have men of genius been much encouraged to 
apply their talents to its advancement : many among the most 
admired specimens of painted glass which ornament our re- 
ligious edifices, are the productions of foreign artists. 

The great church at Gouda, in Holland, is splendidly embel- 
lished with painted windows, which, about the year 1555, were 
executed by various artists, the most celebrated among whom 
were Dirk and Walter Crabeth. The one among the windows 
which is the most highly esteemed was painted by the first 
mentioned of these two brothers ; and Mr. Hollis mentions, as 
evidence of the value placed upon this work of art, that for the 
lower part of this window, — about twenty feet square, — Mr. 
Trevor, some time English resident at the Hague, had in vain 
offered to give a solid plate of gold of the same surface, and of 
the thickness of three Dutch guilders. 

This particular division of the fine arts differs from other 
branches in containing within itself fewer incentives to its pros- 
ecution. Its practice is accompanied by various laborious and 
differing processes. The range of subjects which it admits 
far more circumscribed, and the opportunities which it offers foi 
the display of excellence are far less frequent. The artist is 
even without the gratification of witnessing the satisfactory 



CHAP. XIV. STAINING AND PAINTING GLASS. 225 

progress of his own work, the appearance of which is compara- 
tively dull and uninteresting until after it has passed from his 
own hands into those of " red Lemnos' artisan." The sculptor 
and the painter in oil colors can seldom fail in procuring means 
for exhibiting their works ; so that, according to the degree of 
talent evinced by them will generally be their encouragement 
and reward ; while the man who has conquered every disad- 
vantage attending the processes of staining glass, and who may 
have produced a piece, the conception and execution of which 
are alike honorable to his genius and assiduity, might look in 
vain for the opportunity of bringing its merits before the world. 
These works have, therefore, seldom if ever been undertaken, 
unless at the requirement of others, who, dictating both the 
subject and its details according to their own peculiar tastes 
and wishes, leave nothing wherein the superior talents of the 
artist can be displayed, save the correctness of drawing and the 
elaborateness of execution. A man of genius will not consent 
to be thus trammelled, or follow, for the attainment of a precari- 
ous recompense, one profession, when, by bringing to the exer- 
cise of another the same amount of talent, and far less labor, he 
may at once give scope to his conceptions and advance his 
worldly interests. 

A much wider field than presents itself for the exercise of ' 
this art in England, is certainly offered in Catholic countries, 
where not only is it more in accordance with the feelings of 
the people to ornament their religious edifices, but where a 
much freer scope is given to the artist in the choice of subjects 
for embellishment. Popular legends of the saints in honor of 
whom their churches are named, which are shut out by our 
simpler form of worship and severer religious discipline, afford 
a never-failing source whence these subjects may be drawn ; 
while he who labors for the adornment of a Protestant church, 
is restricted to subjects founded upon mere scriptural authority. 
England has, indeed, within the last half century, produced 
some few proficients in this art, whose productions would do 
honor to any country : but the encouragement extended towards 
these talented individuals has been too limited to raise up, as in 
other pursuits, a succession of masters ; while some, by whom 
it has at first been embraced, have been allured from it by the 
more general and liberal patronage accorded to the professors 
of oil painting. 

Staining and painting on glass differ in some respects from 
all other styles of pictorial embellishment. They agree, how- 
ever, generally with the processes used in painting porcelain, 
not only in the nature of the substances to be embellished, and 
in the materials whence the colors are derived, but likewise for 



226 GLASS MANUFACTURE* CHAP. XIV. 

the most part in the methods used for the application of those 
colors, and in the necessity which exists for fixing them by ex- 
posure to a high degree of heat. The art is, indeed, in most 
particulars, so extremely analagous to the methods employed 
for painting porcelain, and which have already been treated of 
in this volume, that it will not be necessary to occupy much 
space in its description. 

The colors are drawn from the same class of natural sub- 
stances as afford enamel colors ; they are prepared, and for the 
most part are applied, in the same manner ; while any difference 
which may be found to exist in the mode of fixing and bringing 
out the effect of colors by the aid of fire, are more referrible to 
the varied forms of the articles than to any actual difference 
observable between the habitudes of glass and porcelain. 

Boyle, in one of his letters on the subject of imbuing glass 
with metallic colors, wherein are detailed some experiments 
which he himself made in order to obtain a ruby color, relates 
also an anecdote of an artist, who wished, for some purpose, to 
prepare an amalgam of gold and mercury. With this view he 
kept the two metals for some time together in a state of fusion 
in a glass retort, when this at length burst with a tremendous 
explosion. Mr. Boyle adds, that he saw some of the fragments, 
and he declares them to be of the finest ruby color he ever be- 
held. 

Many directions are to be found in the works of old writers 
for the composition of stains and colors. Some of these agree 
very closely with recipes in use at present, while others are 
evidently incorrect or incomplete ; it being impossible, by fol- 
lowing them, to obtain the colors which they are said to fur- 
nish. There appears to have always existed a spirit of exclu- 
sion on the part of professors of this art ; and it has been said 
that this jealousy has even weighed with those among them 
who have written on the subject, so far as purposely to give 
false directions, that students might be deterred from the fur- 
ther prosecution of their attempts. It is more charitable, and 
at the same time more consonant with probability, to imagine, 
that the errors which abound in these works are owing rather 
to the carelessness of transcribers and editors, than to wilful 
misstatements on the part of the authors. Let this be as it may, 
it still is certain that until the period when M. Brongniart pub- 
lished the results of his experiments and practice in regard to 
enamel colors, the public was not in possession of any informa- 
tion whereon reliance could safely be placed for their produc- 
tion. 

Various compositions are recommended to be used with the 
colors as fluxes, in order to promote their fusion when exposed 



CHAP. XIV. STAINING AND PAINTING GLASS. 227 

to the heat of the furnace : these compositions are termed hard ! 
or soft fluxes, in proportion as they require a greater or less 
amount of heat for their perfect fusion, and for the production 
of their full effect upon the metallic oxides with which they are 
joined. In choosing between them, regard must he had to the ' 
peculiar nature of the individual substance or compound where- 
with they are combined, that the flowing of all in fusion may 
take place as nearly as possible together. With this view, it is 
evident that a waste both of time and labor would be experi- 
enced, if any hard flux were used with an oxide which could 
be brought to melt at a low heat ; and, on the other hand, that 
it would be still more improper to use a soft flux with oxides 
which are more refractory, seeing that the proper incorporation 
of the two substances could not possibly in that case be occa- 
sioned. 

Oxide of lead forms a principal ingredient in many fluxes. 
It is necessary, however, to be sparing in its use where it is re- 
quired to produce pink colors, as these would be injuriously 
acted upon by any excessive quantity of lead. Its place may in 
such case be advantageously supplied by borax. 

A fluxing compound, very generally used, is made by the 
union of thirty-two parts of flint glass with twelve parts of 
pearl-ash, and two parts of borax ; which composition will fuse | 
at a medium heat. If it should be required to render this more 
fusible, such an effect may be gained either by substituting for 
the pearl-ash four parts of red oxide of lead, or by increasing 
proportionally the dose of borax ; and if, on the other hand, it is 
desired to produce a hard flux, this end may be attained by 
omitting the borax altogether, and adding an equal quantity of 
common table salt. 

The directions for the preparation of fluxes for porcelain, 
which will be found in another part of this volume, apply equal- 
ly to those which are to be used with glass, and it would be 
therefore useless to repeat them here. 

When enamel colors are applied to glass, they are, besides 
their union with a fluxing material, mixed in the same manner 
as for painting on porcelain, with some substance as a vehicle 
for causing them to flow readily from the brush, and at the same 
time to prevent the colors from blending themselves one with 
the other during the operation. Oil of lavender, balsam of 
capivi, oil of turpentine or of amber, or sometimes gum- water, 
are employed as this vehicle. The choice of any particular 
substance must depend, as in the painting on porcelain bodies, 
upon the nature of the coloring matters employed, and is of no 
real consequence to the ultimate appearance of the glass, since 



228 GLASS MANUFACTURE. CHAP. XIV. 

the whole will be entirely evaporated when submitted to the 
intense heat of the furnace. 

The coloring compounds having been previously ground with 
an appropriate flux upon either a porphyry or strong plate- 
glass palette, by means of a muller of the same material, must 
again be ground in the same manner, and reduced to a proper 
consistency with the vehicle just mentioned. The artist will 
do well to prepare at first a sufficient quantity of every color 
required for the completion of the object which he has in hand ; 
it being extremely difficult, if not impossible, to produce tints 
identically the same at any subsequent time, although the 
greatest attention be paid to the proportions of their ingredients. 
The injury which may be thus occasioned to the beauty of the 
piece need not be insisted upon. 

Many objects may be painted on glass by persons who have 
not acquired any previous knowledge of the art of design. The 
transparent nature of the material enables the artist to see dis- 
tinctly both the outline and the shading of any pattern which 
may be fixed upon its under side. The outlines of every such 
pattern should be decidedly given ; and the whole contour anc 
shading must be at once obvious when looking on its upper 
surface. When the pattern paper is laid horizontally upon the 
glass, it must be secured by wafers at each of its four corners, 
to prevent its shifting ; the glass must then be placed upon an 
easel similar in form to a music-stand, and fixed steadily upon 
the table. Means should also be taken to prevent the slipping 
of the glass upon the easel, by passing a string across its face 
in any position that will secure this object, without interfering 
with the subject intended to be drawn. 

To support the arm of the artist while he is "employed in 
painting, as it would be improper for him to touch the glass, it 
will be necessary to use a rest stick, in the manner observed 
by artists who paint with oil colors. 

It is considered advisable to trace the outline, in the first 
instance, with common Indian ink much diluted, before using 
for the purpose the pencil color, about to be described: the 
reasons for which are, that the strokes will admit of easier cor- 
rection, and that a rough line will be thus formed upon the sur- 
face of the plate, which, drying immediately after the applica- 
tion, serves to direct the point of the brush when charged with 
the color, and to occasion the delivery of the latter with greater 
ease and regularity than would be otherwise attainable : by 
this means the artist may avoid any patching or altering of th( 
outline, which would seldom fail to render the work rougl 
and unsightly, but which must be resorted to if the lines 
prove unequal or imperfect. Faults of this kind may, indeed. 



CHAP. XIV. STAINING AND PAINTING GLASS. 229 

)e partially corrected at any period of the process ; but as the 
glass must be fired anew after each application of color, and 
as the firings constitute the principal part of the expense, it is 
of course advisable to exercise all possible carefulness, in order 
to avoid, as far as possible, the necessity for their repetition. 

The color most usually employed for drawing the outlines 
and for shading different subjects, and which is therefore called 
)y artists outline or pencil color, is made of the saffron-colored 
oxide of iron commonly known in the shops by the name of 
crocus martis. This oxide must be well ground in combina- 
tion with an equal weight of soft flux upon a porphyry or 
ilate-glass palette, as before directed, and subsequently also 
with oil of amber as its vehicle. To provide for the preserva- 
tion of its proper degree of consistency, the addition of one or 
;wo drops of balsam of capivi may be needed ; it is desirable, 
however, to make as sparing use as possible of this substance, 
which sometimes, when evaporated in the intense heat of the 
din, will, through its greasiness, indispose the glass from 
taking the color properly ; and little vacancies may in conse- 
quence be left unoccupied, and requiring to be subsequently 
supplied. The pencil color thus prepared is a dark-reddish 
Drown, and remains unaltered by the heat of the furnace. In 
order that the outline, while it is sufficiently decided, may at 
the same time be fine and clear, the pencil color must be used 
as little moistened as will admit of its flowing from the brush ; 
and until it has become perfectly dry and hard upon the glass, 
no subsequent part of the coloring process should be commenced. 
If when the pattern is wafered on the glass, and the outline 
las been completely traced, it is desired to make one or more 
copies of the figure upon other plates of glass, this may be done 
without removing the paper from the first, by simply placing 
the second and other plates in succession upon that to which 
the pattern is attached, the transparency of which will admit 
f the outlines being traced with the same facility as if the 
attern had been transferred to each individual plate. 

The best crown-glass is generally chosen for painting or 
staining, as being most transparent and free from color. 

The colors must be laid on with a long-haired sable pencil ; 
:ts handle must be of a length which will allow the artist to use 
lis hand with freedom, and should be securely attached to the 
rush, so that the two cannot become disunited. If such an 
ccident were to occur as the falling of this brush charged 
ith color, it would be impossible adequately to repair the mis- 
hief by any means short of obliterating the whole, and begin- 
ing the work anew. 
The shading and coloring are very frequently performed 



S80 GLASS MANUFACTURE. CHAP. XIV* 

upon opposite sides of the glass ; and this condition is almost 
invariably observed where the color to be applied is one which 
can be made to flow with sufficient freedom, or, to use the 
phrase employed by artists, which can be floated on the surface 
of the glass. In cases, too, where it is desired to produce tints, 
such as many shades of green, which would result from the ad- 
mixture of two different colors, this same effect is produced by 
applying one of these to the face, and the other to the reverse, 
of the glass. 

There are only three colors, strictly speaking, which can be 
floated on, and which are called stains, to distinguish them 
from others which must be laid on by the strokes of a brush. 
These stains are orange, red, and lemon-yellow. They are 
composed according to the following recipes : — 

Orange stain. Melt together in a crucible 2 parts grain or 
virgin silver, and one part of crude antimony. When cold, 
this compound must be pounded and sifted ; and when used, 
must be mixed with 6 times its own weight of Venetian red, 
and diluted with cold water to the consistence of cream. 

In floating this stain upon the glass, a large camel-hair pencil 
in a swan's quill, or a flat varnish brush of the same material, 
must be used. The glass should be taken in the left hand, 
while the other is employed in floating the color ; the move- 
ments of the first being so managed, that the stain as it quits 
the brush may float gently and evenly over the surface. lf f 
after this, the glass is placed upon a level table, the stain will 
dry in about twelve hours, when it is in a fit state for the kiln ; 
and upon the application of a moderate heat, a deep gold-colored 
stain will be produced, which will have penetrated the sub- 
stance of the plate, and which will continue unimpaired by 
time. A lighter-colored orange stain may be obtained by in- 
creasing the proportion of Venetian red, relatively to the quan- 
tity of silver and antimony. 

Red stain. In no particular is the difference between an- 
cient and modern stained glass more observable than in the 
absence from the latter of that brilliant scarlet tint, which is 
most generally seen on the first, and the art of producing 
which appears to be lost. The red color which artists are now 
accustomed to employ as a substitute for this, is tame and cold 
in comparison ; and to give it any good effect, requires the aid 
of artifice, in placing it amid brilliant lights, or surrounding itl 
with cold colors. The modern red stain is produced by adding,] 
immediately before it is applied, three drops of sulphuric aei<~ 
to each pint measure of the orange stain last described : pre- 
cisely the same methods must be observed for the applicatioi 
of both. 



CHAP. XIV. STAINING AND PAINTING GLASS. 231 

Lemon-yellow stain. This is made by adding to 1 part of 
pure silver (precipitated) 12 parts of finely powdered pipe-clay, 
These must be mixed together in a basin with cold water to 
the proper consistence, and floated on as before described. The 
tint of this stain may be rendered lighter or deeper by adding 
to or taking from the proportional quantity of the pipe-clay. 
This, as well as the Venetian red, is of no effect in the produc- 
tion of color ; they act only as vehicles assisting to spread the 
metals equally over the surface # of the glass : of course, the 
greater their proportions, the smaller will be the quantity of 
coloring substance upon a given surface, and the lighter will 
be the resulting tint. 

In addition to the above three stains, a fine transparent green 
may be also produced by first staining the glass on one side 
with lemon-yellow, and then painting it on the reverse side 
with a blue color. This combination will certainly not possess 
the same degree of clearness as is imparted by the simple use 
of either of the three stains which have been described, but it 
will have a good effect when used to represent foliage or for- 
draperies in situations where recourse cannot well be had to 
the use of pot metal. 

Where many colors are employed which must be laid on 
with a brush, the artist will apply some to the face, and others 
to the reverse, consulting his own fancy or convenience in re- 
gard to this disposition of the tints. The rule which forbids 
the application of another color, until one previously laid on 
shall be perfectly dry, applies in all cases, and must be ob- 
served as well in covering the opposite surfaces, as when 
various colors are applied to the same side. 

When all the tints are laid on, and are thoroughly dried, the 
glass is ready for the first burning, the manner of conducting 
which will be hereafter described. After this has been per- 
formed, and the glass is removed from the kiln, the artist should 
proceed to scrape off the superfluous colors which remain upon 
its surfaces. If in the performance of this process care is taken 
to remove each one separately, these colors may be ground 
with a fresh portion of the vehicle, and employed on any future 
occasion, as their coloring properties will be perfectly unin- 
jured. The costliness of some enamel colors renders this an 
object of some moment. On the completion of this scraping, it 
will be seen that the glass has been penetrated by the colors ; 
and if due care has been taken in the choice and preparation 
of the coloring materials, and the previous processes have been 
properly conducted, there will be no necessity for any fresh 
application of colors : if even a few spots should appear, they 
will be removed by a second burning, which at the same time 



232 GLASS MANUFACTURE. CHAP. XIV. 

will considerably heighten and bring out the colors. Should 
there, however, be any imperfections either in the stain, or 
painting, or pencil shading, these must be repaired by the artist 
previous to consigning the glass again to the kiln. 

It is sometimes wished to give to glass the appearance of 
having been ground, leaving at the same time transparent lines 
or patterns upon its surface, the effect of which is very pleasing 
to the eye. In preparing for the production of this appearance, 
the artist uses a large camel-hair pencil, the end of which is 
dipped into oil of amber, so as to take up only a small quantity 
at any one time ; and with this, holding the brush perpendicu- 
lar to the glass, every part of the latter must be dabbed so that 
the surface will be dimmed by the oil. This must not lie 
thicker on one part than on another, and should by no means 
be applied in sufficient quantity to give it a fluid appearance. 
Taking then a mixture, composed of one part of white oxide 
of tin, with three parts of flux, previously wellground together, 
this must be sifted from a lawn sieve very gently over the 
glass, until the whole surface is evenly covered. The requi- 
site quantity of this powder will adhere slightly to the glass 
through the means of the oil ; and when, in the course of six 
or eight hours, this has become sufficiently dry, the superfluous 
powder must be lightly removed with a soft brush made of 
badgers' hair. The appearance of the glass will now perfectly 
resemble that which has been ground. 

In order to produce lines or patterns upon its surface, that 
shall have the usual polish and transparent quality of glass, a 
pattern must be drawn upon paper, having its lines sufficiently 
strong to be visible through the powder ; and this being fixed 
upon the reverse side, the artist with a blunt wooden instru- 
ment scrapes off the composition in lines accordant with those 
of the pattern. The plate of glass having then been subjected 
to burning in the kiln, it will be found that the powder has 
been partially melted by the heat, and is so firmly united to the 
glass, that its removal will be extremely difficult. 

It now remains to describe the particular apparatus and pro- 
cess used for burning-in the color^s which have been applied to 
the surface of the glass. The size of the kiln is of course de- 
pendent on the magnitude and number of the pieces of glass 
upon which it may be desired to operate at any one time. It 
would be unwise to construct one of larger dimensions than 
are likely to be needed in use, as the due heating of the glass 
is more difficult and expensive, in proportion as the relative 
size of the furnace is increased. 

The glass is placed during the firing in a close iron box or 
oven, which is called a muffle, and which is provided with hori- 



CHAP. XIV. STAINING AND PAINTING GLASS. 233 

zontal iron shelves placed at regular distances apart, whereon 
the plates are deposited. The relative sizes of the muffle and 
furnace are such, that a space not less than four inches remains i 
between the two on every side, by which means the fire may 
be made wholly to envelop the muffle. This receptacle is pro- 
vided with a tube proceeding from its front, and narrowing to- 
wards its extremity, without-side the furnace wall, the use of 
which tube is to examine the state of the glass from time to 
time during the process of firing. The iron plates for support- 
ing and separating the glass, and which are fitted to the shape 
of the muffle, are kept at their proper distances, usually about 
one inch asunder, by legs of the requisite length placed at their 
four corners. The shape of the muffle is usually wider at the 
top than at the bottom, so that pieces of various dimensions 
may be contained in its different compartments. The number 
of these bears reference to the size of the apparatus, some 
small muffles having no more than five or six, while others of 
greater dimensions are provided with double that number of 
shelves. 

If the plates of glass were placed in immediate contact with 
the iron shelves within the muffle, the metal would have an 
injurious effect upon some colors. The iron is, besides, liable 
to be warped ; and, when the glass was brought into a softened 
state by heat, would communicate its own distorted shape. 
-Another and a greater evil than even these would arise from 
the too sudden variations of temperature whereunto the glass 
would be subjected, owing to the strong conducting power of 
the iron, and which would imminently endanger the cracking 
of the glass. 

A perfect remedy for all these evils is found in previously 
.preparing a smooth and even bed for the glass, by sifting 
pounded whiting to the depth of a quarter or three eighths of 
an inch over the entire surface of the iron shelves. Upon this 
bed the glass must be deposited with every possible care, so as 
to avoid rubbing the colors. 

If more than one piece is committed to each shelf, they must 
on no account be brought into contact, nor must they be al- 
lowed to touch or even to approach within half an inch of the 
side of the muffle. When, after proceeding in this manner, 
the muffle has been filled, or all the glass that is ready for 
burning has been deposited, the cover must be put on to the 
muffle, and the fire lighted. It is usual to employ coke and 
charcoal as fuel for burning glass, both because they afford a 
steadier and more effective heat than coal, and because the sul- 
phur which the latter so commonly contains might have an evil 
effect upon the colors. 

U2 



234 GLASS MANUFACTURE. CHAP. XIV. 

The proper management of the fire in respect to the de- 
grees of heat employed, is a thing which must be acquired 
through practice, it being impossible to give any written direc- 
tions concerning it that will be efficacious, It may, however, 
be stated, generally, that caution is necessary in the first stage 
of heating, so as to avoid all suddenly great accessions of tem- 
perature ; but that when, on inspection, the glass placed in the 
centre of the muffle is seen to have acquired a dull red heat, 
the fire may be urged with safety, so that the whole contents 
of the kiln may be made to acquire an uniform white heat. 
When this effect has once been produced, no more firing is 
requisite ; the fuel which is already in the furnace must be al- 
lowed to burn itself out ; and the kiln remaining thereafter 
closed, must be left to cool gradually during ten or twelve 
hours, before it is attempted to remove the glass : at the end 
of this time it may be considered properly annealed. 

The process of the second or third firing is conducted in pre- 
cisely a similar manner in all respects. 

The same powdered whiting which has already served may 
be used again for an indefinite number of times, upon being 
ground and sifted as for its first application. 

Specimens of ancient stained glass have been occasionally 
found, on parts of which the colors retain their full brilliancy, 
while on other portions they appear to be wholly obliterated ; a 
circumstance which has excited some surprise ; and no little 
ingenuity has been shown in the formation of theories to ac- 
count for this partial disappearance of colors. There is reason 
to believe, however, that no decay has really ensued, but that, 
while some of the colors have been produced upon these speci- 
mens by processes similar to the foregoing description, other 
pieces of glass already stained in the manner of pot metal have 
been applied to uncolored parts, and made to adhere by the in- 
terposition of some fluxing material, which, being softer than 
the glass, has been decomposed in the course of time, and 
these adjunctive pieces have fallen away. 



CHAP. XV. GLASS CUTTING. 235 

CHAP. XV. 

ON THE ART OP CUTTING, ENGRAVING, AND ETCHING ON GLASS. 

Origin of the Art of cutting Glass. — Implements.— Manner of their Employ- 
ment.— Frosting — Patterns produced by Moulding.— Engraving on Glass, 
executed with the Diamond. — Etching. — Schwanhard. — Difference of hia 
Practice from that now used.— Method of Etching.— Fluoric Acid.— Glass 
Incrustations. — Origin of the Art. — Improvements thereon. 

The art of cutting glass is a much more modern invention 
than that of painting and staining it, which has been described 
in the preceding chapter. 

It is generally believed, that Caspar Lehmann, originally a 
cutter of iron and steel in the service of the emperor Rudolphus 
II, was the first person who attempted this mode of embellish- 
ing the material. It was about the year 1609, when, having 
jrocured from the emperor an exclusive patent for using the 
art, together with the appointment of lapidary and glass-cutter 
to the court, Lehmann prosecuted his invention with much suc- 
cess in the city of Prague. 

Before that time, many artists had engraved figures upon 
glass, by means of the diamond ; and their labors were greatly 
admired. Some glaziers had also discovered a mode of cutting 
glass by the employment of emery powder, and sharp pointed 
nstruments of hardened steel, as well as with heated irons ; 
)ut these methods were greatly different in the manner of their 
)erformance, as well as inferior in their effect, to Lehmann's 
)rocess, by which they were consequently, for the most part, 
superseded. It was, however, very long after the period already 
mentioned, that the art attained to any thing like the degree of 
perfection which it now exhibits. 

At the end of the seventeenth century, glass-cutting was 
prosecuted to a great extent, and in a very improved style, at 
Nuremburg ; the artists of that place having much simplified 
the tools employed, as well as the methods used for their em- 
ployment. 

In the present advanced state of the art, the glass utensils 
nd ornaments which contribute so greatly to the embellishment 
f our tables and saloons, owe much of their richness and bril- 
liancy to the elaborate manner in which they are cut. This 

ode of ornamenting glass, although it does not indeed offer 
my field for exercising the higher faculties of genius and in- 
dention, yet calls for a considerable degree of taste in the ar- 
•angement of forms and figures. 

The implements employed by the glass-cutter, although, 
>wing to the great variety of the work which he has to execute, 



236 GLASS MANUFACTURE. CHAP. XV- 

they are of necessity numerous, yet partake of the simplicity 
observable throughout the various processes of the manufacture. 

In some principal establishments, steam power is used for 
giving motion to a shaft which causes the revolution of numer- 
ous large wheels or drums fixed thereon, and each of these being 
connected by a band with a pulley on the axle of a smaller 
wheel, occasions the latter to revolve with great celerity : these 
small wheels are the cutting instruments. The occupation is 
frequently carried on in the apartment of an individual work- 
man, and in this case, only one large wheel, similarly connected 
with the axle of one of smaller diameter, is turned by means of 
a winch, a boy being employed for the purpose. In all other 
respects the process is identical, whether prosecuted in the attic 
of the artisan, or in the spacious factory of the manufacturer. 

The small wheels are so arranged, that each can be unfixed 
without difficulty, and another substituted of a form better suited 
to the work in hand, or of a material more adapted to the stage 
of the process. 

As regards their forms, these cutting wheels are either nar- 
row or broad — flat-edged — mitre-edged, that is, with two faces 
forming a sharp angle at their point of meeting — convex or con- 
cave. In fact, so various are the wants of the workman, that 
as many as forty or fifty wheels having differently shaped edges, 
are to be found in the workshop. 

The materials employed in the formation of these cutting im- 
plements are, iron, both cast and wrought ; Yorkshire stone ; 
and willow wood. Wrought iron is, indeed, only used for cut- 
ters of the narrowest dimensions, and which it would therefore 
not be possible to make sufficiently .tough of cast metal. Iron 
wheels are used only for the first or roughest part of the opera- 
tion, and their employment is even dispensed with altogether,, 
where it is intended that the pattern shall be at all minute ; as 
the metal and the sand, which must be used in conjunction with 
it, would act too roughly, and frequently chip away portions of 
the glass. For such minute works, and for smoothing down the 
asperities which will always be occasioned where iron cutters 
have been applied, a wheel of Yorkshire stone, moistened with 
water, must be used. The further smoothing and subsequent 
polishing of the cut surfaces are effected with wooden wheels : 
for the first of these objects, the edge is dressed with either 
pumice-stone or rotten-stone ; and for imparting the high de- 
gree of polish that is requisite for properly finishing the process, 
putty-powder is employed. 

Beneath each one of the cutting wheels, a small cistern is 
fixed to receive the sand, water, or powder which has been 
used ; and over the wheel, a small keg or a conical vessel iss 



CHAP. XV. GLASS CUTTING. 237 

placed, the cock or opening at the bottom of which is so situated 
and regulated, as that the requisite quantity of moisture will be 
imparted from it to the wheel. The vessel which is placed 
over the iron wheel is furnished with fine sand, and into this 
water is admitted in such quantity as will insure the constant 
delivery of the moistened sand upon the face of the wheel, in 
such proportion as the workman finds most desirable. The 
emery powder, rotten-stone, or putty-powder, are applied from 
time to time as required by the workman, on the edge of the 
smoothing or polishing wheel. 

From this short description of the implements, the manner of 
their employment will be readily comprehended. The glass- 
cutter seats himself on a stool in front of the wheel ; and taking 
in his hand the glass to be ornamented, applies this to the face 
of the cutter, the correctness of his eye and the steadiness of his 
hand being called into requisition, in the successive applications 
to the wheel, of those parts of the glass that are to be cut. 
Placed at his right hand each workman has a small tub con- 
taining water, wherewith from time to time he washes away 
the particles of sand or powder which may adhere to the glass, 
that he may the better judge as to the progress of his work. 

It may readily be supposed that, in conducting a process of 
this nature, with so exceedingly brittle a substance, accidents 
will often occur through the breaking of the material. The 
frequency of these casualties will of course depend, in a great 
measure, upon the original quality of the material ; and this 
forms one reason why the best description of glass is generally 
chosen for the purpose of being cut. 

In fitting up the machinery, it is plain that the utmost accu- 
racy must be exercised. If the cutting- wheels were allowed 
to turn upon their centres with the smallest degree of eccen- 
tricity, it would be quite impossible for the operator to proceed 
with any regularity in his work, or to produce a satisfactory 
effect. 

The wages of glass-cutters, in common with those of men 
employed in the different manufacturing processes of a glass- 
house, are paid according to the work which they deliver in a 
finished and perfect state ; so that if any accident should occur 
to the glass while in their hands, as is frequently the case, the 
workmen cannot claim any payment for the labor which they 
may already have bestowed upon it. Every man who follows 
the occupation of a glass-cutter is capable of executing each 
part of the process, although some will succeed better in one 
branch than in others. In large establishments there is gene- 
rally such a choice of work, that every workman has the op- 
portunity of providing himself with employment in that branch 



238 GLASS MANUFACTURE. CHAP. XV. 

which he prefers ; besides this, two or more men, forming a 
sort of partnership, will frequently undertake work in con- 
junction, each of them performing that branch of the process 
which he feels himself qualified to execute with the greatest 
success, by which division of labor the whole work is more ex- 
peditiously and probably also more satisfactorily performed. 

The grinding of glass, or frosting it, in order to lessen its 
transparency, forms a branch of the glass-cutter's art. The 
objects to which, in the present day, this grinding process is 
most commonly applied, are shades for softening the light dif- 
fused by table lamps. As the roughness is given to the inner 
surface of these glasses, it is plain that they cannot be applied 
to the cutting-wheel for the purpose. Instead of this, the 
shades are, therefore, fixed in a lathe, and the workman, hold- 
ing in his hand a piece of wood which he covers with wet 
sand, causes this to rub with the necessary degree of force 
against the inner surface during the rapid revolutions of the 
glass. 

The amount and description of labor bestowed upon articles 
which pass through the glass-cutter's hands, must necessarily 
enhance their money value, and therefore circumscribe their 
use. Nor is there much reason to look for . the discovery of 
any improvements in the processes whereby that labor can be 
so abridged as that the manufacture will be brought within the 
reach of a larger number of consumers. Under this view, any 
method of ornamenting glass which can be offered as a toler- 
able substitute for cutting it, is likely to be favorably received 
by the public. 

Such an invention has recently been made the subject of a 
patent, under which glass vessels, having a variety of shapes,, 
are formed with ornamental figured patterns impressed upon 
them. 

The method of producing these patterns is sufficiently sim- 
ple, and consists in placing a quantity of melted glass within a 
metallic mould of the required form, in the lower division of 
which the desired pattern is engraved ; and in then bringing 
down the upper section of the mould, and pressing the melted 
glass between the two. The only skill required for the opera- 
tion is that of apportioning rightly the quantity of melted glass 
which is required for exactly filling the mould, so as to take a 
faithful impression of the engraved pattern. The two parts of 
the mould are connected together by means of a hinge, and 
the upper portion is provided with a long handle, which acts as 
a lever for imparting the requisite pressure. The lower sec- 
tion is composed of two pieces, which being opened, the glass 



6HAP* XV e ETCHING ON GLASS. 239 

may be removed from the mould almost at the moment of its 
formation. 

Intended as a substitute for cutting", this art must certainly 
be considered inferior. The patterns imparted by the mould 
are deficient in the degree of sharpness which is imparted by 
the wheel. On the other hand, a description of ornament may 
be thus adopted, which is otherwise unattainable ; the figures 
may be either raised or depressed, and patterns the most minute 
and intricate may be produced. Armorial bearings, in particu- 
lar, may thus be represented, in a manner far superior to any 
engraving, not only as the glass will everywhere retain its 
polish, but also because figures may be given in relief. Be- 
tween the cost of the two processes there cannot be any com- 
parison. 

Many specimens are preserved in collections of ancient glass 
which are ornamented with raised figures. These have been 
most probably produced by pressure within a mould while yet 
softened by heat, such a practice being one of great antiquity. 
Engraved figures were likewise executed upon hollow vessels 
by the old Greek artists; and that celebrated engraver on 
stones, Lawrence Natter, affirms, in his " Treatise on the An- 
tique, when compared with the Modern Method of Engraving 
on Precious Stones," that the same kind of instruments were 
used for the production of these relics of antiquity, as were 
employed for the same purpose at the time when he wrote. He 
considers that the old artists undoubtedly used a wheel, which 
moved in a horizontal direction above the table at which they 
wrought ; and this opinion is in agreement with a passage in 
Pliny (Hist. Nat. lib. xxxvi. cap. 26.) : — " Aliud flatu figura- 
tur, aliud torno teritur, aliud argenti modo crelatur." On the 
other hand, to agree with Natter would be to deprive Lehmann 
of his reputation as an inventor, although he may still be en- 
titled to the honor of having revived an art which had become 
obsolete ; and this, in the opinion of the learned antiquarian 
Caylus, himself the re-inventor of a sister art, is the amount 
of merit whereto Lehmann may justly lay claim. 

• In the middle of the sixteenth century, when glasses manu- 
factured in the Venetian states enjoyed the highest reputation 
throughout Europe, it was common to find these ornamented 
by engravings executed with the diamond. More than an- hun- 
dred years had elapsed from that period, when Henry Schwan- 
hard, a pupil of Lehmann, was incited by the accidental cir- 
cumstance of the corrosion of his spectacle glass, to a method 
of etching on glass by means of some powerful acid liquor. 
His manner of preparing this liquor was kept secret by him ; 
and as no fluid, save fluoric acid, with which we are acquaint- 



240 GLASS MANUFACTURE. CHAP. XV. 

ed, has the property of acting upon the surface of glass, while 
the discovery of this powerful menstruum was not brought be- 
fore the world prior to the publication of Scheele's experiments 
in 1771, it is much to be regretted that the secret of Sch wan- 
hard was suffered to go with him to the grave. 

The method pursued by this artist in the application of his 
discovery was different from that which is practised at present. 
This is, to coat over the entire surface of the glass with var- 
nish, and, through this coating, to trace out the intended fig- 
ures, leaving the glass exposed to the action of the acid only 
in those parts which are to be occupied by the figures. Schwan- 
hard, on the contrary, first traced the figures, and, having filled 
the outline on the glass with varnish, applied his corrosive fluid 
to the remainder of the surface. By this means the figures 
were left in relief, and with their original polish, the effect of 
which was pleasing, and totally dissimilar to the appearance of 
engravings with the diamond, which latter circumstance it 
probably was that incited the artist to the adoption of his pecu- 
liar method, since his productions would, by that means, be 
more readily distinguished from the works of others. 

The varnish employed by artists for defending, where it is= 
requisite, the surface of the glass from the corroding power of 
the acid, is usually either a solution of isinglass in water,, or 
common turpentine varnish mixed with a small proportion of 
white lead. 

By the aid of a very few implements, the art of etching on 
glass may be rendered a pleasing occupation for amateurs. 
Good crown-glass is the most proper to be chosen for this pur- 
pose. Having selected a square pane of the proper size, this 
should be first heated by immersion in a sand-bath, and then 
rubbed over with purified bees'-wax, the temperature of the 
glass being such as to cause the wax to melt completely and 
uniformly over its surface. The pane, thus covered, must then 
be set aside to cool ; and it is important to observe, that every 
part of its face must be protected by this coating of wax; 
which, however, need not be thick, and indeed should not be 
applied in sufficient quantity to render the glass opaque. 

A paper having the design boldly drawn upon it, may then 
be attached to the unwaxed under side of the glass ; and this 
drawing will greatly assist the artist in performing the next 
process, that of tracing the design through the wax. The best 
kind of tool for executing this operation is a carpenter's brad- 
awl, which, as it is flattened at the end in one direction, and 
rounded in another, may, according to the position wherein it 
is held, be easily made to trace lines having the requisite and 
different degrees of fineness. The point of a penknife, or any 



CHAP. XV. ETCHING OF GLASS. 241 

similar implement, may be used as a substitute for the brad-awl, 
and with almost equal efficacy. In tracing these lines, the artist 
must be mindful that his instrument lays bare the surface of the 
glass throughout the whole extent of the strokes. 

A shallow evaporating basin of Wedgwood ware must next 
oe employed. Its size should be such as will include within its 
area every part of the design ; and it must at the same time be 
sufficiently small to be completely covered when the pane of 
glass is made to rest upon its edge. Some coarsely powdered 
fluor spar must then be placed in the basin, together with a 
quantity of strong sulphuric acid, sufficient to form with it a 
thin paste, when the two substances must be well mixed to- 
gether by stirring them. The quantity of fluor spar must of 
course be regulated by the size of the etching ; and it may be 
a sufficient guide on that head, to recommend that two ounces 
of the coarse powder be used when the basin is capable of con- 
taining a pint : these basins are readily procurable from any re- 
spectable dealer in earthenware. 

As soon as the acid and fluor spar are properly incorporated 
together, the pane of glass should be placed upon the basin, 
with the waxed side downwards, and a moderate degree of heat 
must be applied to the bottom of the basin : somewhere between 
120 and 140 degrees of Fahrenheit's scale will be found most 
eligible. Perhaps the best means of providing a steady heat 
for this purpose is offered by the sand-bath, which was used for 
heating the glass before applying the wax. On this subsequent 
occasion, however, the temperature must never be sufficiently 
high to melt the wax, which in that case would run over the 
glass, and wholly destroy the effect of the etching. 

Very soon after this application of heat, fumes of fluoric acid 
will rise copiously from the basin, and attack the unprotected 
portions of the glass. When the basin and its contents are once 
thoroughly warmed, the heat of the sand-bath may be advan- 
tageously diminished. 

After the glass has been thus exposed during half an hour, 
it may be removed from the basin ; and first being rinsed in 
water, for the purpose of diluting or washing away the fluoric 
acid, the wax may be scraped off with a common table-knife ; 
the design will then be found perfectly etched upon the surface 
of the glass. 

A metallic basin will answer perfectly for generating the flu- 
oric acid ; but it will be altogether improper to use any glazed 
vessels for the purpose, as the vitreous coating of such would be 
entirely destroyed. 

In performing this process, it is necessary to use some cau- 
tion ; as fluoric acid, if brought into contact with the skin, will 



242 GLASS MANUFACTURE. CHAP. XV« 

quickly disorganize it, and produce wounds which may be pain- 
ful and troublesome ; a very little carefulness will, however, 
suffice for preventing any accident of this nature. 

When it is required thus to engrave other than plane sur- 
faces, another arrangement must be provided : the glass must 
be exposed to the fumes of fluoric acid in some deep vessel ; 
without, however, being suffered to come in contact with the 
pasty compound whence the acid fumes arise ; and the whole 
should be covered over, to confine and retain those fumes, so 
that they may fully act upon the glass. 

Articles made of flint glass are sometimes very tastefully or- 
namented, by inclosing within their substance various objects 
formed out of bodies which, being less fusible than glass, will 
not be altered in their form or nature by the heat contained in 
this at the moment of their introduction. 

The art was first attempted about fifty years ago, by a glass 
manufacturer in Bohemia, who sought to incrust small figures 
made with a grayish kind of clay. His success in this attempt 
was but moderate ; the material of which he made choice for 
his figures, expanded and • contracted very unequally with the 
surrounding glass, and their adhesion to it was consequently 
imperfect. 

The successful accomplishment of this pleasing art has long 
been a favorite object with the French manufacturers, who 
have been unsparing of expense in their efforts for its perfec- 
tion. For a long time, however, their success was small, and 
the specimens produced by them were so costly, that but little 
encouragement was offered on the part of purchasers. The 
subject at that time principally chosen for the exercise of this 
art, was a medallion of Napoleon, whose courtiers evinced the 
desire of possessing his likeness in this imperishable form, as 
being emblematic of their own unalterable attachment ! Im- 
provements have since been made by the French artists, which 
have enabled them to reduce the cost of these incrustations 
within more moderate bounds; but their manufacturers have 
hitherto mostly restricted themselves to the ornamenting in this 
manner of scent-bottles and trinkets. 

A few years ago one of the most considerable London glass 
manufacturers discovered the means of attaining to a higher de- 
gree of success, and is now enabled thus to ornament, in a very 
tasteful manner, various objects of considerable size ; employing 
for the purpose substances whose property it is to expand and 
contract equally with glass upon exposure to altered tempera- 
tures. This interesting art can by this means be applied to 
represent ornaments of almost every description. The appear- 
ance most usually given to them is that of silver ; but as the 



chap. xvi. Reaumur's porcelain. 243 

metallic oxides may be employed for coloring the substances 
previous to their incrustation, every variety of hue that can be 
used in enamel painting may also be imparted. . 



CHAP. XVI. 

ON THE DEVITRIFICATION OF GLASS. 

First observed by Neumann.— Experiments of Reaumur.— Substance known 
as Reaumur's Porcelain. — Inappropriateness of this name. — Uses to which 
the Substance may be applied.— Common Bottle Glass most proper for this 
Conversion.— Method of effecting the Change.— Produced solely by Heat. 
—Experiments of Dr. Lewis.— Re vitrification.— Experiments of Sir James 
Hall.— Proposal suggested thereby.— Observations of Guyton-Morveau.— 
Artificial Intaglios.— Mock Onyxes.— Power of Devitrified Glass to bear 
sudden Changes of Temperature.— Experiments with Colored Glass. — 
Glass devitrified by burning Lava.— The Process promoted by multiply- 
ing the Ingredients of Glass.— Devitrified Glass conducts Heat more per- 
fectly that when vitreous.— Becomes a Conductor of Electricity.— Retains 
this Property when revitrined. 

It was observed very long since by Neumann, that some 
kinds of glass, if exposed during any considerable time to a 
high degree of heat, but below their point of fusion, are so far 
changed in their properties and texture as to become opaque, 
fibrous, and tough ; and so hard as to give abundant sparks if 
struck with steel, to cut any common glass readily, and to be 
scarcely susceptible of abrasion by filing. It has also been 
found, that in taking this form, glass so far alters its nature as 
regards its qualities of expansion and conducting of heat, that 
it will bear a sudden transference from freezing to boiling 
water. 

That indefatigable naturalist, M. Reaumur, made various 
experiments and observations on this phenomenon ; and, in the 
year 1739, communicated the result of these to the Royal Acad- 
emy of Sciences in Paris. The subject becoming by this means 
more generally known, glass, when thus converted, obtained, 
and has since kept the name, of Reaumur 's porcelain ; a desig- 
nation whiph it owes to its appearance rather than to its real 
properties, which do not at all entitle it to be classed with por- 
celain. It is probably owing to the inappropriate name which 
the substance thus acquired, that so little has been done to- 
wards a true development of the facts and circumstances at- 
tendant upon the devitrification of glass. Even the greater 
number of such scientific men as for a time entered upon the 
investigation, limited their labors to experiments with various 
cementing substances, that they might arrive at the discovery 



244 GLASS MANUFACTURE. CHAP. XVI. 

of that one which would insure the concurrence of the greatest 
number of good qualities that should be found in porcelain. 
The futility of these experiments has since been made evident ; 
and it must be regretted that the same amount of research as 
was thus unprofitably bestowed, has not been given to elucidate 
the actual properties of devitrified glass, and to render it prac- 
tically serviceable to society. 

Reaumur was of opinion that its quality of resisting alterna- 
tions of temperature, its toughness, as well as the power it pos- 
sesses of withstanding the action of acid liquids, render this por- 
celainous glass well qualified for the formation of chemical ves- 
sels. The same opinion has been equally held and declared by 
other philosophers who have brought their minds to the inves- 
tigation of the subject; and it appears singular that their sug- 
gestion should not, consequently, have been very generally re- 
duced to practice. This circumstance must further excite sur- 
prise, when it is considered in how many important operations 
of the laboratory such a substitute for metallic vessels would be 
advantageous. In operating upon any practical scale, the 
chemist is driven, for want of such a substitute, either to the 
employment of metals which are liable to be injuriously acted 
upon by the matters under process, or is compelled to adopt 
vessels of platinum, the expensiveness of which places them 
beyond the prudent reach of most persons. In* one instance, a 
manufacturer of pharmaceutical preparations, who is exceed- 
ingly particular as to the absolute purity of his productions, has 
recently incurred the expense of constructing a pan of unalloy- 
ed silver, forty inches in diameter, wherein to evaporate vege- 
table extracts, many of which, in some degree or other, act 
upon and are impregnated by copper. 

Could vessels formed of this fibrous glass be adopted with 
safety, there would be nothing in their cost, especially when of 
moderate size, to prevent their general adoption. The only 
circumstance hitherto assigned against this adoption is, that al- 
though the inner texture of the glass is fine and white, the sur- 
face is coarse and of a dirty appearance ; but this must be 
thought a very insufficient cause for foregoing such decided 
advantages as are apparently offered through its employment. 

All kinds of glass are not equally qualified to undergo this 
conversion ; with some descriptions, indeed, it will not ensue. 
Not any vitreous compound seems altogether proper, for it, with 
the exception of common green bottle-glass, and perhaps also 
the ordinary kinds of window glass. 

The method commonly employed for # effecting the change is 
as follows : — The glass vessel is placed within a larger earthen 
iressel, in the same manner as is pursued for baking porcelain. 



chap. xvi. Reaumur's porcelain. 245 

The entire space unoccupied by the glass is next filled by pour- 
ing into the vessel fine white sand, or powdered gypsum, so 
that the glass shall not be allowed at any point to come into 
contact with the earthen case. The containing vessel is then 
covered down, securely luted, and the whole is placed within 
the furnace. 

It was for some time generally imagined, that in this process, 
which is very similar to that which is known to chemists under 
the name of cementation, the glass owes the change which it 
undergoes to some chemical action of the gypsum upon its sub- 
stance : but this has been proved erroneous. It is shown by Dr. 
Lewis, in the detail of his various experiments, that not only 
may the nature of the powder be almost infinitely varied, with- 
out in the least affecting the operation, as far as regards the al- 
tered texture of the glass, but that the change equally and iden- 
tically goes forward in the absence of all cementing substance ; 
a fact which is conclusive upon the subject, and which proves 
that whatever may be the particular substance employed, 
whether sand, bone-ash, chalk, or gypsum, it acts merely by af- 
fording mechanical aid, sustaining the glass in its proper form 
during the period when it is softened by heat, and when, if de- 
prived of such support, it would be liable to irreparable injury 
in falling together by means of its own gravity. 

In the course of experiments, which are detailed by him at 
some length,* Dr. Lewis placed several pieces of common wine 
bottles into crucibles, pouring over them the requisite quanti- 
ties of white sand, and placing them in a proper furnace, where- 
in they were heated during many hours. In order to ascertain 
the progress of the change, pieces were withdrawn from time to 
time for examination. Those pieces which were first taken out, 
after having been during several hours in the furnace, but with- 
out being heated to redness, exhibited no sort of change what- 
ever. In a low red heat the change went forward very slow- 
ly, but still was quite perceptible ; while in a strong red heat 
approaching to whiteness, and which only just avoided that de- 
gree of in tenseness which would have melted the glass, the 
change went on rapidly, beginning at each surface, and spread- 
ing towards the middle ; so that, in two hours, the substance 
had assumed throughout the appearance of porcelain. 

The glass became first of a bluish color on the surface, and 
exhibited a very sensible diminution of its transparency. After 
this, it gradually became white and more opaque ;, the texture 
no longer continued vitreous, but became fibrous, as already de- 
scribed ; and these fibres were disposed nearly parallel to each 

* Commercium Philosophico-technicum, p. 150, 

V2 



246 GLASS MANUFACTURE. CHAP. XVI. 

other, and transverse to the thickness of the piece. The fibres 
from both surfaces meeting in the middle, formed there a kind 
of partition, in which cavities were occasionally perceptible. 
By degrees this opacity and fibrous change were completed, the 
blue color disappeared, and was succeeded by a dull white or 
dun color. 

When exposure to the same high degree of heat was con- 
tinued after the production of this effect, the glass was seen to 
undergo a still further change of-texture : the fibres appeared 
to be divided or cut into grains ; beginning, as before, at the 
outer ends, and proceeding onwards towards the middle, until 
the entire substance assumed a granular form, similar to ordi- 
nary porcelain. A still further continuance of heat caused the 
grains, which at first were fine and glossy, to become enlarged 
and dull, and to change from a compact to a porous, and at 
length to a friable substance, resembling a slightly cohering 
mass of white sand, not easily distinguishable from that wherein 
it was embedded. 

If glass, which has been withdrawn from the furnace at the 
time it has assumed the fibrous state, be afterwards subjected to 
a very strong heat, it will melt into a semi-transparent mass, 
and may be drawn out in strings, which on cooling are found to 
have lost their fibrous quality, and to have resumed their for- 
mer vitreous state, being no harder than before the original 
cementation. This fusion of porcelainous glass cannot, how- 
ever, be effected, without the application of a degree of heat 
considerably more intense than is required for melting glass in 
its more usual form ; and it is also found that the farther the 
process of cementation has been carried, the higher must the 
temperature be raised for its fusion ; so that specimens which 
have been rendered granular are much more refractory than 
such as are simply fibrous. 

Although, throughout the experiments of Dr. Lewis, no dif- 
ference in the actual properties of Reaumur's porcelain follow- 
ed the employment of different substances for embedding the 
glass, — its internal color, hardness, texture, and the regular 
succession of its changes being the same in all cases ; — yet con- 
siderable difference was occasioned in its outward color. If 
charcoal or soot had been used, these produced a deep black 
color, which was not affected by long exposure to heat in an 
open furnace. Clay or sand which was colored, communicated 
different shades of brown ; and white earths gave either gray 
or brown tinges. The greatest degree of whiteness followed 
upon the use of white sand, calcined flints, or gypsum ; and the 
highest state of glossiness or brightness was caused by the em- 
ployment of pipe-clay. 



chap, xvi. Reaumur's porcelain. 247 

In the account published by Sir James Hall of his highly in- 
teresting course of experiments on the effects of compression 
in modifying the action of heat upon a certain class of substan- 
ces, incidental mention is made of an important circumstance 
connected with this change in the texture of glass, and which 
seems to point the way towards the institution of a further 
course of useful investigations. 

Having placed in the closed end of a porcelain tube a portion 
of the substance which he was about to subject to the action of 
heat under pressure, it became necessary to introduce likewise 
within the tube some other substance, which could be brought 
to such a state as would oppose an effectual barrier against the 
communication of the principal substance with the atmosphere. 
The use of various bodies was attempted for this purpose, and 
each was successively rejected as inadequate. Among these, 
Sir James determined upon trying the effect of pounded glass; 
which, being placed within the tube, above and nearly in con- 
tact with the principal substance, could be subjected to such a 
degree of heat as would fuse the glass, while the closed end of 
the tube might be sufficiently withdrawn from the action of the 
furnace ; and when, in the prosecution of the actual experiment, 
this end should come to be placed in the strongest heat, that 
portion of the tube in which the then compact body of glass was 
contained could be equally removed from a temperature which 
would again alter its form. 

The description of glass accidentally chosen by Sir James 
Hall for his experiment, was that which is best of all qualified 
for conversion into Reaumur's porcelain. Having introduced 
the tube wherein the pounded glass was contained within a 
muffle heated to the temperature of 20° of Wedgwood's scale, 
3677° Fahrenheit, he discovered, that in the space of one 
minute it entered into a state of viscid agglutination, similar to 
that of honey ; and that when only one more minute had elaps- 
ed, the entire particles were consolidated into a firm compact 
mass of Reaumur's porcelain : during the short period here men- 
tioned, the heat of the muffle had been uniformly sustained at 
the same degree. 

If a solid cylinder of glass, having the same bulk as the pow- 
der thus placed within the tube, had been exposed to the same 
temperature, it would equally have undergone a change from 
the vitreous to a fibrous state ; but the time required would 
have amounted to at least an hour. 

The result of the discovery thus unexpectedly made.by Sir 
James Hall, renders it probable, that if common green bottle- 
glass, previously ground to powder, were introduced within ap- 
propriate moulds, and exposed to an adequate temperature, it 



248 GLASS MANUFACTURE. CHAP. XVI. 

would speedily and satisfactorily be converted into vessels of 
Reaumur's porcelain ; and by this means, not only would the 
time expended be materially abridged, and fuel economized, 
but the manufacturer would be relieved from one of the great- 
est practical difficulties which has been found to attend the 
conversion, and which arises from the tenacity wherewith the 
sand usually employed is found to adhere to the glass. 

This evil is frequently experienced to so great a degree, that 
the force required for their separation endangers the breaking 
of the vessel. Moulds of every requisite form might be made 
without difficulty, of substances sufficiently refractory to remain 
uninfluenced by the temperature employed for the conversion, 
and which would deliver the glass freely upon its completion. 

M. Guyton-Morveau read, in 1810, before the French Na- 
tional Institute, a paper containing observations with a view to 
explain some phenomena that occur in the fabrication of glass* 
In the course of his remarks, this celebrated chemist drew the 
attention of his auditors to several specimens of devitrified glass 
collected by him, which had been rendered opaque and fibrous 
by the long-continued action of heat in a porcelain furnace. 
Some of these pieces were converted, without having been sur- 
rounded by sand or gypsum, or any other cementing substance, 
and yet exhibited the completest change throughout their sub- 
stance. 

One of his specimens, composed of bottle glass, had been ex- 
posed, during three entire days, to the heat of 50 degrees of 
Wedgwood's pyrometer, and had acquired interiorly a rosy tint, 
its fracture exhibiting fibrous lines, arranged in the form of 
stars, and converging towards the centre : this glass was suffi- 
ciently hard to scratch rock crystal. Another specimen of flint 
glass, which had been exposed during the same time, in the 
same furnace, exhibited only the commencement of crystalliza- 
tion at its surface ; the interior retaining, unaltered, its original 
vitreous quality. 

M. Guyton-Morveau likewise exhibited some artificial intag- 
lios, made of bottle glass, which had been first softened and 
moulded in a cupelling-furnace, on an impression taken with 
rotten-stone, and subsequently devitrified in the heat of a por- 
celain furnace. These specimens were sufficiently hard to 
scratch rock-crystal ; a quality which points out the fitness of 
such productions to be used as dies for the preparation of in- 
taglios and cameos, the impression which they receive and im- 
part being exceedingly chaste and perfect. The same quality 
suggests the advantage that would probably be found in the em- 

* Ann. de Chim. vol. lxxiii. p. 113. 



chap. xvi. reaumijr's porcelain. 249 

ployment of Reaumur's porcelain in the composition of mock 
onyxes ; but, for this purpose, the ground and figures must be 
formed of separate layers of different-colored glass, which must 
be brought together by means of some fluxing material, and 
afterwards devitrifled, in order to give them the requisite opa- 
city, and, in some degree, also, that hardness which is the dis- 
tinguishing characteristic of gems. 

One specimen, also brought forward on the same occasion by 
M. Guyton-Morveau, was a segment of a globe, composed of 
bottle-glass, which had been cut in the form of a watch-glass, 
to be used as a capsule, and afterwards devitrifled. This piece 
might be suddenly heated red-hot, and immediately thrown into 
cold water, without experiencing injury. It might also be kept 
in heated sulphuric acid, without exhibiting the least corrosion 
or alteration of weight; two qualities calculated to render its 
employment eminently advantageous for the purposes of chem- 
ical analysis. 

The result of different experiments made to devitrify stained 
glass taken from church windows, was likewise shown, on the 
same occasion, by M. Guyton-Morveau. Of various pieces thus 
treated, some were colored red by the precipitate of Cassius, 
and others blue by oxide of cobalt. One of the red specimens 
contained lead in its composition ; this, on losing its transparent 
quality, had become of a spongy consistency, and appeared full 
of blebs ; in the other piece, which was hard crown-glass, the 
devitrification was seen to have pursued its usual and regular 
course, interiorly from the two surfaces : it had acquired a pur- 
ple tinge, and was so little hardened that it might be scratched 
by rock-crystal. The piece which had been stained by oxide 
of cobalt differed from the last in more than one particular. Its 
hardness was so great, that scarcely could any perceptible mark 
be made upon it by adamantine spar ; its blue color, which had 
the appearance of being somewhat weakened internally, was at 
the same time more intense at the surface, a variance which 
might, indeed, be more apparent than real, and which probably 
resulted from the greater opaqueness it had acquired at that 
part; as although the glass had lost all transparency, the devi- 
trification was by no means perfect, having proceeded but a 
short distance below the surface. 

Glass has been converted into Reaumur's porcelain during 
volcanic eruptions, by being enveloped in burning lava. Some 
specimens of this kind were obtained after the destruction of 
Torre del Greco, in 1794 ; but it is somewhat remarkable, that 
this devitrifying effect has been by no means uniformly exhibit- 
ed under the same circumstances, since pieces of glass have 
been found, which, although completely embedded between two 



250 GLASS MANUFACTURE. CHAP. XVI. 

opaque volcanic crusts, yet retain their transparency and vitre- 
ous qualities. The examination of these particular specimens 
does not appear to have been carried sufficiently far to deter- 
mine the fact ; but it is by no means unlikely that the varying 
effect here noticed may have been owing to some difference in 
their original composition. 

The greater the number of suitable ingredients that are em- 
ployed in the composition of glass, the more easily and promptly 
does it become devitrified. This circumstance will sufficiently 
account for the fact of bottle-glass being the most suitable of 
any for conversion into Reaumur's porcelain. Having been 
compounded without much attention to the purity of its ingre- 
dients, this substance contains a great variety of earthy salts in 
minute quantities; while plate glass, which is a much more 
simple body, and in the manufacture of which the purified in- 
gredients are brought together in the precise proportions that 
are required exactly to saturate each other, can be devitrified 
only partially, and with great difficulty. 

On the other hand, in the same manner as a solution com- 
pounded of a great variety of saline bodies forms its crystalline 
deposits in a confused manner, so is it also observed that the 
fewer the number of ingredients which are contained in devit- 
rified glass, the greater is the degree of regularity whereby its 
fibrous arrangement is attended ; and for this reason plate glass, 
where the difficulty attending its devitrification has been over- 
come, furnishes, if not the most complete, yet certainly the 
most regular and beautiful specimens of Reaumur's porcelain. 

It has been observed that glass, when devitrified, becomes a 
much more perfect conductor of heat and electricity than it was 
before it had changed its vitreous form. In fact, several pieces 
of glass, when converted into Reaumur's porcelain, could not 
be made to exhibit any sign of electricity by friction. This 
circumstance is rendered yet more remarkable by the fact, that 
glass which, having been once devitrified, has been made to 
resume its vitreous form by fusion, although it is thereby re- 
invested with its original density, fracture, and other charac- 
teristics, yet shows no greater disposition to become electric 
than it exhibited during its state of devitrification. 



INDEX. 



A. 

A1KIN, Messrs., their experiments 
on the composition of glass, 133 
Alhot, M. his experiments on the 
manufacture of bottle glass, 152. 
Alumina, 34. 

Astbury discovers the Elers' method 
of glazing porcelain, 25. 
Aristotle, his problems respecting 
glass. 108. 
Atlilianus, 20. 

B. 
Bamboo of Wedgwood, 28. 
Basaltes of Wedgwood, 28. 
Beads, manufacture of, 182. Imita- 
tion of pearl, 184. Manner of their 
invention and formation, ib. 
Bede, the venerable, his account of 
glass in England, 112. 
Blancourt, his account of the dis 
covery of casting plate-glass, 114. 
Blowpipe, description of, 177. 
Blunging, process of, 41. 
Bricks, antiquity of the manufacture 
of, 18. Roman manufacture of, ib. 
Brindley.his improved flint-mill, 42. 
Brongniart, M., his receipt for the 
manufacture of tender porcelain, 46. 
Buckingham, second duke of, his en 
couragement of the manufacture of 
British glass, 115. 
C. 
Carlsbad, mineral springs of, 36. 
Caylus, Count, his account of ancient 

colored glass, 219. 
Chaptal, M., his direction for making 
glass from calcined bones, 175. His 
process for forming white enamel,63. 
Clay, analysis and description of, 34. 
Wedgwood's experiments on, ib. 
Further analysis of, 35. Species of, 
used in the potteries of Staifordshire, 
37. Blue clay the best, 38. China 
clay, ib. Dilution of, in potteries, 40. 
Cobalt, oxide of, used as coloring 
matter in the manufacture of por- 
celain, 21. 

Colbert, Monsieur, patronizes the 
manufacture of glass in France, 113. 
Cookworthy, his manufacture of por 
celain, 29. 
Crazing, meaning of the term, 37. 

D. 

De Botticher, baron, discovers the 
composition of true porcelain, 22. 

D'Entrecolles, Francis Xavier, mis- 
sionary in China, 22. 

DeMontamy,M.,his recipe for com 
posing a pure white color, 77. 

De Montigny, M., furnace of, 57. 

De Palissy, Bernard, his improve 
ments in enamelling, 64. His dis 
tresses and perseverance, 65. 

Dial-plates of watches and clocks, 
how formed, 185. Lettering and 
figuring, 188. 

Durcos, M., his experiments on the 
manufacture of bottle glass, 152. 

K. 

Elers, the two brothers, their manu- 
facture of porcelain, 25. 

Enamel, coloring, antiquity of, 69. 
F. 

Faraday, Mr., his experiments re- 
specting the manufacture of heavy 
glass, 134. 

Felspar, Cornish, its fusibility, 39. 

Flint, analysis of, 36. Process for 
the preparation of, for the manufac- 
ture of porcelain, 42. 

Fontanieu, M., his direction for the 
composition of artificial gems, 171. 
His recipe for the color of the ame- 
thyst, 215 ; of the emerald, fl6. His 
receipt for the lustre of the semi- 
transparent opal, 218. 

Frauenhofer, rises from obscurity by 
bis talents; his scientific acquire- 



ments, 201. Produces specimens of 
perfect glass ; dies at an early age, lb 



G. 

Gehlen, M., his recipe for orown 
glass, 145. 

Gems, composition of, 35. 
Gems, artificial; great interest for- 
merly attached to the subject, 171. 
Modes of preparation, ib. Rock 
crystal formerly employed, 172. 
Diamond paste, 173. Various pastes 
for imitating different gems, 174. 
Geobert, M., his analysis of the por- 
celain earth of Baudissero, 39. 
Gerhard, his experiments on granite, 
38. 

Glass, nature of, 105- Its various 
properties, ib. Its utility, 106. 
Value of it anciently, 107. Origin 
of the word ; Aristotle's problems 
respecting it, 108. A Phenician in- 
vention, ib. Manufactories of Alex 
andria, 109. Malleable glass, ib. 
Discussion on the malleability of, 
110. Tax imposed on by Alexander 
Severus; Portland vase; employed 
in forming windows, 111. Manufac- 
tured in Britain prior to the Ro- 
man invasion, ib. Extract from 
the "Northumberland Household 
Book," 112. Privileges granted to 
manufacturers in France, ib. Plate 
glass casting, 113. Establishment 
at St. Gobain, 114. Flint glass, 
manufacture of, commenced in Eng- 
land, 115. Plate glass manufactured 
in England, ib. Chinese unacquaint- 
ed with glass-making, 116. Import- 
ance of the manufacture in England, 
ib. Madeasourceofrevenue,117. In- 
gredients employed in the manufac- 
ture of, 119. Silex and alkali essen- 
tial to the formation of glass ; pot- 
ash and pearl-ash used also, 120. 
Barilla ; kelp, ib. Borax and chalk 
used in the manufacture of, 124. 
Construction of a furnace for, 125. 
Three kinds of furnaces used in the 
manufacture of, 126. The calcar; 
the fritting process, ib. Double fur- 
nace; proportionate dimensions of 
furnace and pots, 128, Comparative 
consumption of fuel in wood and 
coal furnaces ; annealing oven, 129. 
Glass pots : their formation and sea 
soiling, 130. Manufacture of flint 
glass, 131. Importance of its quality 
for optical purposes; experiments 
for its improvement, 132. Process 
of melting, 134. Glass gall, 135. Im 
plements used in the manufacture 
of; rod, 136. Marvar, 137. Paraison 
blowing, ib. Re-heating; elongat 
ing, 138. Pontil, ib. Procello; 
fashioning, 139. Detaching, ib. Re- 
moval to annealing oven; mould 
ing; annealing indispensable, 140. 
Bologna phials; Rupert's drops, ib. 
Crown glass, description of, 143. Its 
composition in France ; in England ; 
fritting, 144. Recipes for crown 
glass, 145. Blowing; re-heating; 
flattening, 146. Twirling ; expand- 
ing; opening, 147. Bull's eye, ib. 
Annealing ; nice regulation of tern 
peraturein this process ; qualities of 
crown glass, 148. Broad glass ; in- 
ferior to crown glass ; its composr 
tion ; preparation, ib. Working ; 
bursting ; annealing, 149. Bottle 
glass; manufacture of, checked by 
an increase of duty, lb. Composi- 
tion; restrictions as to materials; 
their bad tendency. 150. Superiority 
of, for certain purposes, ib. Mate- 
rials employed; in France ; at New- 
castle, 151. Fashioning; moulding, 
ib. Experiments of Count Chaptal, 
152. Klingsteiu, 153. Volcanic gra- 



nite, 154. Plats glass: blown plates 
limited in size, ib. Cast plate works 
at Ravenhead; difficulties of the 
process; materials, 155. Furnaces 
and crucibles at St. Gobain, 107. 
Method for regulating the supply of 
fuel at St. Gobain, 158. Casting 
tables, ib. Arrangement of the foun- 
dery at Ravenhead, 159. Process of 
casting plates, ib. Squaring; grind- 
ing, 161. Economical improvement; 
smoothing ; emery powder, 162. 
Comparative value of large and 
small plates, 163. Polishing, 164. 
Silvering, 165. Preparation of amal- 
gam, ib . Mode of its application, 166. 
Process of blowing, 167. Punching, 
168. Partial cutting, ib. Transfer 
to pontil ; completion of cutting, 169. 
Opening, ib. Sizes of plates ; effects 
of the sun's rays on, 170. Phos- 
phoric glass, preparation of bones 
for ; their vitrification ; process 
known to Becher; concealed by 
him, 175. Curious suggestion as to 
its employment: this glass highly 
electric when newly made, ib. Va- 
rious small manufactures of glass, 
176. Thermometer, 177. Blow-pipe, 
ib. Method of working, 178. Seal- 
ing tubes, ib. Bending and joining 
tubes, 179. Forming bulbs at the 
ends of tubes, 180. Watch gla&ees, 
ib. Lunette glasses; glass beads r 162. 
Striped tubes ; mode of forming 
beads, 183. Mock pearl beads, 184. 
Principal defects observable in glass, 
192. Striae ; threads, 193. Tears, 
ib. Knots; bubbles; whence they 
proceed, 194. Bubbles not very det- 
rimental, ib. Specific gravity of, 
202. Augmented by lime, 204. Mix- 
ed glasses, 205. Their specific 
weight, 206. Specific gravity in- 
fluenced by temperature, 207. The 
art of coloring it, and the antiquity 
of the art ; specimens of Rom;ui 
mosaic, 208. Analysis of these by 
Klaproth, 209. Metallic oxides, 2 i 0. 
Gold-purple ; its great coloring pow- 
er, ib. Kunckel's proficiency in the 
art of staining glass, 211. Directs 
the operations of glass-houses at Pot«- 
dam, 212. Yellow color from silver; 
from lead, ib. From tartar; from 
beech-wood charcoal, 213. From 
oxide of iron, green, black glass, ib. 
Red, 214. Blue : directions found 
in old authors, 215. Imitation of 
the garnet ; of the amethyst, ib. Of 
the emerald, 216. Of sapphires, ib. 
Opaque glass; black, 217. White 
opaque glass, ib. Opal, 218. Ancient 
pictures formed of colored glass, ib. 
How executed, 219. Accidental col- 
oring of plate glass at St. Gobain, 
221. The art of cutting, engraving, 
and etching on; origin of the art of 
cutting, 235. Implements used in 
cutting, ib. Frosting, 238. Patterns 
produced by moulding, ib. Engrav- 
ing on glass, 239. Etching, 240. In- 
crustations ; origin of the art, 242. 
The devitrification of, 243. Devit- 
rified glass; uses to which it may 
be applied, 244. Common bottle 
glass best suited to it; method of 
effecting the change, ib. Experi- 
ments of Dr. Lewis, 245. Revitri- 
fication of, 246. Experiments of 
Sir James Hall, 247. Glass con- 
verted into Reaumur's porcelain, 
by burning lava, 249. 
Glazes for porcelain generally ; analy- 
sis of that used by the French, 64. 
Green, Mr., proprietor of Stangate 
glass-house; his specimens of good 
heavy-glass, 195. 
Guinand, M., his humble origin ; 
energy of character, 195. Examine* 



252 



telescopes, and constructs others ; 
unable to procure glaas of good qual- 
ity, 19G. Is incited to examine into 
the causes of inferiority; his extra- 
ordinary perseverance amidst acci- 
dents and difficulties, 197. His ulti- 
mate success, 198. Accident lead- 
ing to further improvement, 199. 
Trosecutes his art in Bavaria; re- 
turns home, and further pursues his 
favorite object, 200. Dies, 201. , 

H. 

Hall, Sir James, he experiments on 
compression in modifying the action 
of heat, 247. 

Han way, Jonas, his account of Chi- 
nese palace at Dresden, 24. 

Herculaneum, utensils of glass found 
in the ruins of, 109. 

J. 

Jao tcheou, precious jewels of, 97, 
Jaquin, M., his invention of mock- 
pearl, 184. 
Jasper-ware of Wedgwood, 28. 



Kao-lin, analysis of, 93. 

Keysler, his description of a mode of 
composing pictures in colored glass, 
220. 

Kia-tsing. 99. 

King-te-chiug, porcelain manufacto- 
ries of, 94. 

Klaproth, his investigations respect- 
ing the capability of dissolving silex 
in water, 36. His analysis of the 
epecimens of Roman mosaic, 209, 
His analysis of ancient blue glass, 
ib. His account of ancient mosaics 
220. 

Ku-tong, 101. 

L. 

Lathe, potter's, description of, 48. 

Lenses, formation of; preparation of 

, the necessary tools, 189. Choice of 

■ glass for, 190. Grinding and polish 
ing, ib. 

Loysel, M.,his direction for the con 
etruction of a furnace in themanu 
facture of glass, 125. Recommend! 
the use of minium in the manufac- 
ture of flint glass, 132. His recipe 
for the formation of crown glass 
144. His account of the composl 
tion of bottle glass in France, 151. 
His account of the composition of 
plate glass, at St. Gobain, 156. His 
recipe for the composition of arti- 
ficial gems, 173. His experiments 
on the specific gravity of glass, 202. 

Lunette-glasses, manufacture of, 182. 

Lustre-ware, gold and silver, 60. 

M. 

Macquer, his remarks on Reaumur's 
experiments concerning porcelain, 
23. Furnace of, 57. 

Manganese, black oxide of, used for 
clearing glass, 122. 

Mansell, Sir Robert, obtains a mo- 
nopoly for manufacturing glass in 
England, 115. 

Modeller, qualifications requisite for, 

Morveau, Monsieur Guyton, his ex- 
periments on the specific gravity of 
melted glass, 121. His observations 
on the devitrification of glass, 248. 

Moulds, method of making them, 52. 

N. 

Neri, his recipe for imitating the 
garnet, 215. His recipe for white 
opaque glass, 218. 

Neumann, first observes the devitri- 
fication of glass, 243. 

Nungarrow, factory, superiority of 
He porcelain, 56. I 



INDEX. 

p. 

Pipes, tobacco, manufacture of prose- 
cuted to a great extent ; description 
of material, 86. Boring, moulding, 
polishing, baking, 87. Description 
of the kiln of crucibles, 88. Manu- 
facture of, prosecuted to a great ex- 
tent in Holland; 89. Originally con- 
veyed thither from England, ib. 
Polo, Marco, his mention of the por- 
celain manufacture of China, 96. 
Porcelain, 17. Antiquity of, 18. 
Made in Japan at an early period, 
20. Oriental porcelain common in 
Europe in the first century, ib. An- 
tiquity of the manufacture of in 
Egypt, 21. Probable origin of the 
word, ib. Manufactured in Saxony 
by baron de Botticher, 22. Reau 
mur's experiments respecting, 23. 
Hanway's account of that manufac- 
tured at Dresden, 24. Antiquity of 
manufacture in Staffordshire, 25. 
Manufactured by the two brothers 
named Elers, ib. Manufacture of, 
important to England, 30. Manu- 
factured at Lambeth ; Derby; Shrop- 
shire; Yorkshire; at the Rocking- 
ham works, 31. A tax imposed 
upon stone bottles, 33. Ingredients 
used in the manufacture of pottery, 
34. The quality of clay used in the 
manufacture of, ib. Steatite or soap- 
stone used in the manufacture of, 
39. Spuma maris used in its manu- 
facture, 40. Quality of water used, 
ib. The process of blunging, 41. 
Process for preparing the flint, 42. 
Utility and description of Brindley's 
mill in the preparation of, ib. Slip; 
slip-kiln, 43. Slip-house, 44. The 
process of slapping in the manufac- 
ture of, 45. Method of manufactur- 
ing in France not kept so secret as 
that in England, ib. Calcined bones 
used in the manufacture of, 46. The 
earth used in Berlin, 47. The for- 
mation of utensils in the manufac- 
ture of; the process of throwing, 
48. Milled edges; the handler, 51. 
Method of ornamenting porcelain 
described, ib. Method of making 
moulds, 52. Boiled plaster used 
making moulds, ib. Increasing skill 
of artists, 53. Mould-maker; meth 
od of his working, 54. Method of 
casting, ib. Seggars of imperfect 
materials in England; Nungarrow 
factory, 57. Furnace of MM. de 
Montigny and Macquer, 57. Th 
biscuit-oven of Worcester ; Chinese 
method of firing, 60. Duration of 
the baking process ; oven-man ; trial 
pieces, 61. Composition of raw 
glazes ; bad effects of them 
Glazes generally, 63. Inferior glazes ; 
low-priced wares, 66. Regulation of 
temperature, ib. Qualities of good 
porcelain; stone-ware, 67. Painted 
ware of Worcester ; of Stafford 
shire; of Derby; of Yorkshire, 69. 
Metallic oxides, 70. Addition of 
fluxing bodies necessary, ib. Ve- 
hicle used with the colors, 73. Pur- 
ple and -violet, 74. Red, 75. Yel- 
low, ib. Blue, 76. Green; brown; 
black, 77. White, 78. Compound 
colors, 79. Gilding ; lustre-ware ; 
preparation of colors, 80. Enamel- 
ling kilns, ib. Trial pieces, 81. Gild- 
ing and burnishing, ib. Analysis of 
the fluxes and recipes for colors, 83. 
Method of transferring copperplate 
designs to porcelain, 84. French 
method, 85. Manufacture of in Chi- 
na, 90. Supposed superiority of old 
China-ware, ib. Materials employ- 
ed ; kao-lin ; pe-tun-tse ; their pre- 
paration, 91. Oils fit varnishes; 
their composition, 92. Hao-che 
superior to kao-lin, 93. Analysis of 
kao-lin, ib. Extent of factories at 
King-te-ching ; great number of 

THE END 



workmen, 04. Preparation of ma- 
terials, ib. Method of fashioning 
utensils ; moulds, ib. Division of 
labor, 95. Deficiency of the Chinese 
in the art of design, 96. Blue first 
the only color used, 97. Chinese 
ignorant of chemical science, 98. 
Umiam; tsou-tchi, 99. Kia-tsing 
method of forming it, ib. Chinese 
furnaces, 100. Passion for old por- 
celain, 101. Ku-tong, ib. Mock 
antiques; reasons for the costliness 
of China-ware in Europe, ib. Por- 
celain tower, ib. Tse-ki; attempt 
of the emperor to transfer the ma- 
nufacture to Pekin, 102. 
Pottery, antiquity of, 18. Made in 
England before the invasion of the 
Romans, 19. Antiquity of in China, 

Pyrometer of Wedgwood, 35. 

R. 

Reaumur, experiments of, concern- 
ing the manufacture of china, 23. 
His experiments upon the devitri- 
fication of glass; his porcelain, 243. 

Rockingham, the, porcelain manu- 
factory, 31. 

Rose, Mr. John, his glaze for hard 
porcelain, 63. 

Rykum, boiling fountain at, 36. 



Schwanhard, Henry, his method of 
etching on glass, 240. 

Seggars, proper materials for the con- 
struction of them wanting in Eng- 
land, 55. Use of, 56. 

Severus, Alexander, his tax on glass, 
111. 

Silica, 34. Analysis of, 36. 

Slapping, the process of, 45. Per- 
formed by steam power, 46. 

Slip, the mixture used in porcelain, 
manufacture, 43. 

Spuma maris, its employment in 
porcelain works in Spain, 40. 

Steatite, or soapstone, Cornish, analy- 
sis of, 39. 

St. Gobain, glass manufactory at, 114. 
Its early failure and revival, ib. 

Stone-ware, its composition, 67. Best 
description of it made at Lambeth, 
ib. 

T. 

Table-ware of Wedgwood, 27. 

Terra-cotta of Wedgwood, 28. 

Thevart, his invention of plate glass, 
113. 

Thermometer tubes, 176. Mode of 
giving them an elliptical bore, 177. 

Throwing, the process of, 48. 

Tower-porcelain, at Nan-king, 101. 

Tsou-tchi, 99. 

Turning-lathe of the potter, 49. 

V. 

Vasa, Murrhina, formed out of a 

transparent stone, 20. 
Vase, Portland or Barberini, 53. 

Farther account of, 111. 

W. 

Watch-glasses, manufacture of, 180. 
Lunette-glasses, 182. 

Webber models of Portland or Bar- 
berini vase, 53. 

Wedgwood, Josiah, his improvement 
in the manufacture of porcelain, 
26. His table-ware, 27. Queen's- 
ware; terra-cotta; basaltes; white 
porcelain biscuit; bamboo; jasper, 
28. His porcelain biscuit used by 
chemists, ib. His evidence before 
a committee of the privy council, 29. 
His pvrometer, 35. His encour- 
agement to artists, 53. His great 
services in the painting of porce- 
lain, 69. 

White porcelain biscuit of Wedg- 
wood, 28. 



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" The editors and publishers should receive the thanks of the present 
generation, and the gratitude of posterity, for being the first to prepare in 
this language what deserves to be entitled not the ENCYCLOPAEDIA 
AMERICANA, but the people's library." — N. Y. Courier and Enquirer. 



Just Published, by Carey fy Lea, 

And sold in Philadelphia by E. L. Carey $• A. Hart ; in New- York by 
G. jr C.fy H. Carvill ; in Boston by Carter fy Hendee ; in Baltimore by E. 
J. Coale, fy W. <jr J. Neal ; in Washington by Thompson § Homans ; in 
Richmond by J. H. Nash ; in Savannah by W. T. Williams ; in Charleston 
by W. H. Berrett ; in New-Orleans by W. M'Kean ; in Mobile by Odiorne 
fy Smith ; and by the principal booksellers throughout the Union. 

VOLUME 9, 
CONTAINING ABOUT 1,500 ARTICLES, 

{To be continued at intervals of three months,) 

OF THE 

ENCYCLOPEDIA AMERICANA: 

A 

POPULAR DICTIONARY 

OF 

ARTS, SCIENCES, LITERATURE, HISTORY, AND POLITICS, 

BROUSHT DOWN TO THE PRESENT TIME, AND INCLUDING A COPIOUS 
COLLECTION OF ORIGINAL ARTICLES IN 

AMERICAN BIOGRAPHY: 
On the basis of the Seventh Edition of the German 

CONVERSATIONS-LEXICON. 



Edited by FRANCIS L1EBER, 

ASSISTED BY 

EDWARD WIGGLESWORTH and T. G. BRADFORD, Esqrs. 



IN TWELVE LARGE VOLUMES, OCTAVO, PRICE TO SUBSCRIBERS, 
BOUND IN CLOTH, TWO DOLLARS AND A HALF EACH. 

EACH VOLUME WILL CONTAIN BETWEEN 600 AND 700 PAGES. 



'THE WORLD-RENOWNED CONVERSATIONS-LEXICON."— Edinburgh 

Review. 

11 To supersede cumbrous Encyclopaedias, and put within the reach of the poor- 
est man, a complete library, equal to about forty or fifty good-sized octavos, em- 
bracing every possible subject of interest to the number of 20,000 in all— provided 
he can spare either from his earnings or his extravagancies, twenty cents a week, 
for three years, a library so contrived, as to be equally suited to the learned and 
the unlearned,— the mechanic— the merchant, and the professional man."— JV. Y. 
Courier and Inquirer. 

" The reputation of this valuable work has augmented with each volume; and 
if the unanimous opinion of the press, uttered from all quarters, be true, which 
in this instance happens to be the case, it is indeed one of the best of publica- 
tions. It should be in the possession of every intelligent man, as it is a library 
in itself, comprising an immense mass of lore upon almost every possible sub- 
ject, and in the cheapest possible form."— JV. Y. Mirror. 



ENCYCLOPAEDIA AMERICANA. 



More than half of the volumes of this work are now before the public, 
and the reception they have met with is the best evidence that the publish- 
ers have fulfilled the promises made at its outset. They have now only to 
promise, for the editors and themselves, that no exertion shall be spared to 
render the remaining volumes equal to those already published, and thus 
sustain the reputation it has acquired. The subscription is large, and in- 
creasing; and in those quarters where its circulation is greatest, and where 
it is best known, there is a constantly increasing demand. The publishers 
invite the attention of those who may not already have possessed themselves 
of it, or may not have had an opportunity to become acquainted with its 
merits, to the following account of the original work, upon which it is 
based, and which is termed by the Edinburgh Review — 

THE WORLD-RENOWNED LEIPZIG COxWERSATIONS LEXICON. 

It was intended to supply a want occasioned by the character of the 
age, in which the sciences, arts, trades, and the various forms of know- 
ledge and of active life, had become so much extended and diversified, 
that no individual engaged in business could become well acquainted with 
all subjects of general interest ; while the wide diffusion of information 
rendered such knowledge essential to the character of an accomplished 
man. This want, no existing works were adequate to supply. Books treat- 
ing of particular branches, such as gazetteers, &c. were too confined in 
character; while voluminous Encyclopaedias were too learned, scientific, 
and cumbrous, being usually elaborate treatises, requiring much study or 
previous acquaintance with the subject discussed. The conductors of 
the Conversation Lexicon endeavored to select from every branch of 
knowledge what was necessary to a well-informed mind, and to give poput 
lar views of the more abstruse branches of learning and science ; tha- 
their readers might not be incommoded, and deprived of pleasure or im- 
provement, by ignorance of facts or expressions used in books or conversa- 
tion. Such a work must obviously be of great utility to every class of 
readers. It has been found so much so in Germany, that it is met with 
everywhere, among the learned, the lawyers, the military, artists, mer- 
chants, mechanics, and men of all stations. The reader may judge how 
well it is adapted to its object, from the circumstance, that though it now 
consists of twelve volumes, seven editions, comprising about one hun- 
dred thousand copies, have been printed in less than fifteen years. It 
has been translated into the Swedish, Danish and Dutch languages, and a 
French translation is now preparing in Paris. 

In the preparation of the American edition, no expense has been spared 
to secure the ablest assistance, and the editors have been aided by many 
gentlemen of distinguished ability. 

The American Biography, which is very extensive has been furnished 
by Mr. Walsh, who has long paid particular attention to that branch of 
our literature, and from materials m the collection of which he has been 
engaged for some years. For obvious reasons, the notices of distinguished 
Americans will be confined to deceased individuals: the European biogra- 
phy contains notices of all distinguished living characters, as well as 
those of past times. 

The articles on Zoology and the various branches of Natural Science, 
and those on Chemistry and Mineralogy, have been prepared expressly for 
this work by gentlemen distinguished in the several departments. 

In relation to the Fine Arts, the work is exceedingly rich. Great atten- 
tion was given to this in the German work, and the Editors have been 
anxious to render it, by the nacessary additions, as perfect as possible. 

To gentlemen of the Bar, the work will be peculiarly valuable, as in 
cases where legal subjects are treated, an account is given of English, 
French, German and American Law. 



ENCYCLOPAEDIA AMERICANA. 



" Witnesses from every part of the country concurred in declaring that the 
Encyclopaedia Americana was in a fair way to degrade the dignity of learning, 
and especially the learning of Encyclopaedias, by making it too cheap — that the 
multitudes of all classes were infatuated with it in saying in so many words 
from the highest to the lowest, ' the more we see of the work the better we like 
it.' " — JV* Y Courier and Inquirer. 

"The articles in the present volume appear to us to evince the same ability 
and research which gained so favorable a reception for the work at its com- 
mencement. The Appendix to the volume now before us, containing an account 
of the Indian Languages of America, must prove highly interesting to the reader 
in this country; and it is at once remarkable as a specimen of history and phi- 
lology. The work altogether, we may again be permitted to observe, reflects 
distinguished credit upon the literary and scientific character, as well as the 
scholarship of our country." — Charleston Courier. 

"The copious information which this work affords on American subjects, 
fully justifies its title of an American Dictionary; while at the same time the 
extent, variety, and felicitous disposition of its topics, make it the most conve- 
nient and satisfactory Encyclopaedia that we have ever seen." — NationalJournal. 

" If the succeeding volumes shall equal in merit the one before us, we may 
confidently anticipate for the work a reputation and usefulness which ought to 
secure for it the most flattering encouragement and patronage." — Federal Gazette. 

" The variety of topics is of course vast, and they are treated in a manner 
which is at once so full of information and so interesting, that the work, instead 
of being merely referred to, might be regularly perused with as much pleasure as 
profit." — Baltimore American. 

" We view it as a publication worthy of the age and of the country, and can- 
not but believe the discrimination of our countrymen will sustain the publish- 
ers, and well reward them for this contribution to American Literature."— Bal- 
timers Patriet. 

"It reflects the greatest credit on those who have been concerned in its pro- 
duction, and promises, in a variety of respects, to be the best as well as the most 
compendious dictionary of the arts, sciences, history, politics, biography, &c. 
which has yet been compiled. The style of the portion we have read is terse 
and perspicuous; and it is really curious how so much scientific and other in- 
formation could have been so satisfactorily communicated in such brief limits." 
— JV. Y. Evening Post. 

" A compendious library, and invaluable book of reference." — JV. Y. American. 

" Those who can, by any honest modes of economy, reserve the sum of two 
dollars and fifty cents quarterly, from their family expenses, may pay for this 
work as fast as it is published ; and we confidently believe that they will find at 
the end that they never purchased so much general, practical, useful information 
at so cheap a rate." — Journal of Education. 

" If the encouragement to the publishers should correspond with the testimony 
in favor of their enterprise, and the beautiful and faithful style of its execution, 
the hazard of the undertaking, bold as it was, will be well compensated ; and 
our libraries will be -enriched by the most generally useful encyclopedic diction- 
ary that has been offered to the readers of the English language. Full enough 
for the genera! scholar, and plain enough for every capacity, it is far more con- 
venient, in every view and form, than its more expensive and ponderous prede- 
cessors " — American Farmer. 

"The high reputation of the contributors to this work, will not fail to insure 
it -a favorable reception, and its own merits will do the rest. 1 '— Silliman's Journ. 

"The work will be a valuable possession to every family or individual that 
can afford to purchase it ; and we take pleasure, therefore, in extending the 
knowledge of its merits. 1 '— National Intelligencer. 

"The Encylopaedia Americana is a prodigious improvement upon all that has 
gone before it ; a thing for our country, as well as the country that have it birth, 
to be proud of; an inexhaustible treasury of useful, pleasant, and familiar learn- 
ing on every possible subject, so arranged as to be speedily and safety referred to 
on emergency, as well as on deliberate inquiry; and better still, adapted to the 
understanding, and put within the reach of the multitude. * * * The Ency- 
clopaedia Americana is a work without which no library worthy of the name 
can hereafter be made up."— Yankee. 



ENCYCLOPEDIA AMERICANA. 



"This work appears to improve as it issues from the press. The number of 
able writers, who contribute original matter in all the departments of literature 
and science is amply sufficient to give it celebrity and high character. To men 
engaged in the active pursuits of life — whose time is precious— this popular dic- 
tionary is a most valuable and ready mode of reference. It embraces brief 
views and sketches of all the late discoveries in science— and the present condi- 
tion of literature, politics, &x. &c. Every merchant's counting-room— every 
lawyer's library — every mechanic— every farmer ought to possess a copy of this 
useful and valuable work." — Courier. 

"From the specimen which has already been given, we have no hesitation in 
saying, that in regard to intelligence, skill, and faithful diligence, it is a work 
of the very highest order. We know of no similar publication that can bear 
any comparison with it for the rich variety of valuable information, which it 
condenses within so small a compass. It is free from all the narrowness of Eng- 
lish prejudice, it contains many important and interesting details which can be 
found in no English production, and is a work which could be written by none 
but German scholars, more than two hundred of whom were employed in the 
original compilation." — Boston Observer. 

"This cannot but prove a valuable addition to the literature of the age."— 
Mer. Advertiser. 

" The vast circulation this work has had in Europe, where it has already been 
reprinted in four or five languages, not to speak of the numerous German edi- 
tions, of which seven have been published, speaks loudly in favor of its intrinsic 
merit, without which such a celebrity could never have been attained. To every 
man engaged in public business, who needs a correct and ample book of refer- 
ence on various topics of science and letters, the Encyclopaedia Americana will 
be almost invaluable. To individuals obliged to go to situations where books 
are neither numerous nor easily procured, the rich contents of these twelve vol- 
umes will prove a mine which will amply repay its purchaser, and be with diffi- 
culty exhausted ; and we recommend it to their patronage in the full conviction 
of its worth. Indeed, it is difficult to say to what class of readers such a book 
would not prove useful, nay, almost indispensable, since it combines a great 
amount of valuable matter in small compass, and at moderate expense, and is 
in every respect well suited to augment the reader's stock of ideas, and powers 
of conversation, without severely taxing time or fatiguing attention." — Am. 
Daily Advertiser. 

"The department of American Biography, a subject of which it should be dis- 
graceful to be ignorant, to the degree that many are, is, in this work, a promi- 
nent feature, and has received the attention of one of the most indefatigable 
writers in this department of literature, which the present age can furnish." — 
Boston Courier. 

" According to the plan of Dr. Lieber, a desideratum will be supplied ; the sub- 
stance of contemporary knowledge will be brought within a small compass; — 
and the character and uses of a manual will be imparted to a kind of publica- 
tion heretofore reserved, on strong shelves, for occasional reference. By those 
who understand the German language, the Conversation Lexicon is consulted ten 
times for one application to any English Encyclopaedia." — National Gazette. 

" The volume now published is not only highly honorable to the taste, ability, 
and industry of its editors and publishers, but furnishes a proud sample of the 
accuracy and elegance with which the most elaborate and important literary 
enterprises may now be accomplished in our country. Of the manner in which 
the editors have thus far completed their task, it is impossible, in the course of a 
brief newspaper article, to speak with adequate justice." — Boston Bulletin. 

" It continues to be particularly rich in the departments of Biography and 
Natural History. When we look at the large mass of miscellaneous knowledge 
spread before the reader, in a form which has never been equalled for its conden- 
sation, and conveyed in a style that cannot be surpassed for propriety and per- 
spicuity, we cannot but think that the American Encyclopaedia deesrves a 
place in every collection, in which works of reference form a portion."— South- 
ern Patriot. 

" By far the best work of the kind ever offered for sale in this country ."- 
U. S. Gaz 



CABINET CYCLOPAEDIA, 

CONDUCTED BY THE 

REV. DIONYSIUS LARDNER, LL.D. F.R.S. L.&.E. 
M.R.I. A. F.L.S. F.Z.S. Hon.F.C.P.S. M. Ast. S. &c. &c. 

ASSISTED BY 

EMINENT LITERARY AND SCIENTIFIC MEN. 



Now Publishing by Carey fy Lea, and for sale by all Booksellers. 

This work will form a popular compendium of whatever is useful, instructive, 
and interesting, in the circle of human knowledge. A novel plan of publication 
and arrangement has been adopted, which presents peculiar advantages. With- 
out fully detailing the method, a few of these advantages may be mentioned. 

Each volume will contain one or more subjects uninterrupted and unbroken, 
and will be accompanied by the corresponding plates or other appropriate illus- 
trations. Facility of reference will be obtained without fettering the work by 
a continued alphabetical arrangement. A subscriber may omit particular vol- 
umes or sets of volumes, without disintegrating his series. Thus each purchaser 
may form from the ''Cabinet" a Cyclopaedia, more or less comprehensive, as 
may suit his means, taste, or profession. If a subscriber desire to discontinue 
the work at any stage of its publication, the volumes which he may have re- 
ceived will not lose their value by separation from the rest of the work, since 
they will always either be complete in themselves, or may be made so at a trifling 
expense. 

The purchasers will never find their property in this work destroyed by the 
publication of a second edition. The arrangement is such that particular vol- 
umes may be re-edited or re-written without disturbing the others. The " Cabi- 
net Cyclopaedia'* will thus be in a state of continual renovation, keeping pace 
with the never-ceasing improvements in knowledge, drawing within its circle 
from year to year whatever is new, and casting off whatever is obsolete, so as to 
form a constantly modernized Cyclopaedia. Such are a few of the advantages 
which the proprietors have to offer to the public, and which they pledge them- 
selves to realize. 

Treatises on subjects which are technical and professional will be adapted, 
not so much to those who desire to attain a practical proficiency, as to those 
who seek that portion of information respecting such matters which is generally 
expected from well-educated persons. An interest will be imparted to what is 
abstract by copious illustrations, and the sciences will be rendered attractive, by 
treating them with reference to the most familiar objects and occurrences. 

The unwieldly bulk of Encyclopaedias, not less than the abstruse discussions 
which they contain, has hitherto consigned them to the library, as works of only 
occasional reference. The present work, from its portable form and popular style, 
will claim a place in the drawing-room and the boudoir. Forming in itself a 
Complete Library, affording an extensive and infinitely varied store of instruc- 
tion and amusement, presenting just so much on every subject as those not pro- 
fessionally engaged in it require, convenient in size, attractive in form, elegant 
in illustrations, and most moderate in expense, the "Cabinet Cyclopaedia" will, 
it is hoped, be found an object of paramount interest in every family. 

To the heads of schools and all places of public education the proprietors trust 
that this work will particularly recommend itself. 

It seems scarcely necessary to add, that nothing will be admitted into the 
pages of the " Cabinet Cyclop.edia" which can have the most remote tendency 
to offend public or private morals. To enforce the cultivation of religion and 
the practice of virtue should be a principal object with all who undertake to 
inform the public mind ; but with the views just explained, the conductor of this 
work feels these considerations more especially pressed upon his attention. 
Parents and guardians may, therefore, rest assured that they will never find it 
necessary to place a volume of the " Cabinet " beyond the reach of their children 
or pupils. 



LARDNER S CABINET CYCLOPAEDIA 



Considerable progress having been made in this work, the publishers 
wish to direct the attention of the public to the advantages by which it 
is distinguished from other similar monthly publications. 

It is not intended that the Cabinet Cyclopaedia shall form an intermi- 
nable series, in which any work of interest which may present itself from 
time to time can claim a place. Its subjects are classified according to 
the usual divisions of literature, science, and art. Each division is distinctly 
traced out, and will consist of a determinate number of volumes. Al- 
though the precise extent of the work cannot be fixed with certainty, yet 
there is a limit which will not be exceeded ; and the subscribers may look 
forward to the possession, within a reasonable time, of a complete library 
of instruction, amusement, and general reference, in the regular form Of 
a popular Cyclopaedia. 

The several classes of the work are— 1, NATURAL PHILOSOPHY; 2, 
The USEFUL and FINE ARTS; 3, NATURAL HISTORY; 4, GEOG- 
RAPHY; 5, POLITICS and MORALS; 6, GENERAL LITERATURE 
and CRITICISM ; 7, HISTORY ; 8, BIOGRAPHY. 

In the above abstruse and technical departments of knowledge, an at- 
tempt has been made lo convey to the reader a general acquaintanre with 
these subjects, by the use of plain and familiar language, appropriate 
and well-executed engravings, and copious examples and illustrations, 
taken from objects and events with which every one is acquainted. 

The proprietors formerly pledged themselves that no exertion should 
be spared to obtain the support of the most distinguished talent of the age. 
They trust that they have redeemed that pledge. Among the volumes 
already published in the literary department, no less than four have been 
the production of men who stand in the first rank of literary talent, — Sir 
James Mackintosh and Sir Walter Scott. In the scientific department, a 
work has been produced from the pen of Mr. Herschel, which has been 
pronounced by the highest living authority on subjects of general philoso- 
phy, to contain "the noblest observations on the value of knowledge 
which have been made since Bacon," and to be " the finest work of phi- 
losophical genius which this age has seen." 



The following is a selection from the list of Contributors. 

The Right Honorable Sir JAMES MACKINTOSH, M.P. 

The Right Rev The Lord Bishop of Cloyne. 

Sir WALTER SCOTT, Bart. 

JOHN FREDERICK WILLIAM HERSCHEL, Esq. 

THOMAS MOORE, Esq. 

J. B. BIOT, Member of the French Institute. 

ROBERT SOUTHEY, Esq. Poet Laureate. 

The Baron CHARLES DUPIN, Member of the Royal Institute and 

Chamber of Deputies. 
THOMAS CAMPBELL, Esq. T. B. MACAULEY, Esq. M.P. 

DAVID BREWSTER, LL.D. J. C. L. SISMONDI, of Geneva. 

Capt HENRY KATER, Vice President of the Royal Society. 
Tne ASTRONOMER ROYAL. DA VIES GILBERT, Esq. M.P. 

S. T. COLERIDGE, Esq. JAMES MONTGOMERY, Esq. 

The Right Hon. T. P. COURTENAY, M.P. 
J. J. BERZELIUS, of Stockholm, F.R.S., &c. 
The Rev. G. R. GLEIG. 
T. PHILLIPS, Esq. Prof, of Painting, R.A. 
Rev. C. THIRLWALL, Fellow of Trinity College, Cambridge. 
ANDREW URE, M.D. F.R.S. &c. &c. &e. 



DR. LARDNER'S 
CABINET CYCLOPEDIA. 



VOLUMES PUBLISHED. 



L II.— HISTORY of SCOTLAND. By Sir Walter Scott. 

HI. VI.— HISTORY of ENGLAND. By Sir James Mackintosh. In 
8 Vols. Vols. I. and II. 

[V.— OUTLINES of HISTORY. 

V.— HISTORY of the NETHERLANDS. By T. C. Grattan, Esq. 

VII. VIII. XII.— HISTORY of FRANCE. By Eyre Evans Crowe. In 
3 Vols. 

IX.— MECHANICS. By Capt. Kater and Dr. Lardner, (complete.) 

X.— A PRELIMINARY DISCOURSE on the OBJECTS, ADVAN- 
TAGES, and PLEASURES of the STUDY of NATURAL PHI- 
LOSOPHY. In 1 Vol. By F. J. W. Herschel, Esq. 

N B. — This work forms the Introduction or Preface to the Cabinet 
of Natural Philosophy in the Cyclopaedia. 

XL— BIOGRAPHY of EMINENT BRITISH STATESMEN. 

XIII.— HYDROSTATICS and PNEUMATICS. By Dr. Lardner. 

XIV— HISTORY of the PROGRESS and PRESENT SITUATION 
of the SILK MANUFACTURE. 

XV.— HISTORY of the ITALIAN REPUBLICS. By J. C. L. Sismondi. 

XVI.— HISTORY of the PROGRESS and PRESENT SITUATION 
of the MANUFACTURE of PORCELAIN and GLASS. With 
numerous cuts. 

VOIiUMES IN IMMEDIATE PREPARATION. 

HISTORY of ENGLAND. Vol. III. 

HISTORY of MARITIME and INLAND DISCOVERY. In 3 Vols. 

LIVES of EMINENT BRITISH LAWYERS. In 1 Vol. By H. Ros- 
coe, Esq. 

The HISTORY of the WESTERN WORLD. In 4 Vols. Vol. I. The 
UNITED STATES of AMERICA. 

Two volumes of this work, nearly ready, will complete the History 
of the United States to the present time. The two remaining volumes 
will be devoted to South America and the West India Islands. 

A HISTORY of IRELAND, to the UNION. In 2 Vols. By T. Moore, 
Esq. 

A PRELIMINARY DISCOURSE on the USEFUL ARTS and MANU- 
FACTURES. By the Baron Charles Dupin, Member of the Institute 
of France and of the Chamber of Deputies. 

A HISTORY of the MOORS. In 3 Vols. By Robert Southey, Esq. 

LIVES of the MOST EMINENT LITERARY MEN of ALL NA- 
TIONS. In 8 Vols. By Scott, Southey, Moore, Mackintosh, 
Montgomery, Cunningham, and all the principal Literary and Scien- 
tific Contributors to the Cyclopaedia. 

A TREATISE on ASTRONOMY. By J. F. W. Herschel, Esq. 

GEOGRAPHY. In 4 Vols. By W. Cooley, Esq. author of the " History 
of Maritime Discovery." 

LIVES of the MOST DISTINGUISHED BRITISH NAVAL COM- 
MANDERS. By R. Southey, Esq. 

LIVES of the MOST DISTINGUISHED BRITISH MILITARY COM* 
MANDERS. By the Rev. G. R. Gleig. 

The HISTORY of GREECE. In 3 vols. By the Rev. C. Thirlwall. 

LIVES of EMINENT BRITISH ARTISTS. By W. Y. Otley, Esq. 
and T. Phillips, R. A. Professor of Painting to the Royal Academy. 

A TREATISE on ELECTRICITY and MAGNETISM. By M. Biot, 
Member of the French Institute. 



LARDNER S CABINET CYCL0P2EDIA. 



'BOOKS THAT YOU MAY CARRY TO THE FIRE, AND HOLD READILY IN YOUR 
HAND, ARE THE MOST USEFUL AFTER ALL. A MAN WILL OFTEN LOOK AT 
THEM, AND BE TEMPTED TO GO ON, WHEN HE WOULD HAVE BEEN FRIGHTENED 
AT BOOKS OF A LARGER SIZE, AND OF A MORE ERUDITE APPEARANCE." 

Dr. Johnson. 

44 We advisedly call the Cabinet Cyclopaedia a great undertaking, because we 
consider, that ill its effects on the tone and habits of thought of what is known 
by the phrase, ' the reading public,' it will be, if carried through in the spirit of 
its projection and commencement, one of the most invaluable productions of 
modern literature. * * 

" But these advantages, eminent as they undoubtedly are, are not the sole nor 
the chief recommendations of the Cabinet Cyclopaedia. Neither is it on the ex- 
treme cheapness of the publication, nor the federal independence— if we may so 
speak— of its several volumes, that we rest our prediction of its influence on the 
tone of thinking of the present, and on the literature of the next generation— 
but on the promise, amounting almost to a moral certainty, of the great excel- 
lence of its execution. A multitude of persons eminent in literature and science 
in the United kingdom are employed in this undertaking; and, indeed, no others 
should be employed in it ; for it is a truth that the profound and practised writer 
alone is capable of furnishing a ' popular compendium.' 

44 What parent or guardian that throws his eye over the list of its contributors 
but must be rejoiced by meeting the names of those who are in themselves a 
guarantee of intellectual and moral excellence T"— Literary Gazette. 

44 The plan of the work appears well adapted to the purpose it is proposed to 
fulfil— that of supplying a series of publications, embracing the whole range of 
literature and science, in a popular and portable form; while the excellence of 
the execution is guarantied by the judgment displayed in the selection of writers. 
The list of authors employed in this ambitious undertaking comprises some of 
the most eminent men of the present age." — Mlas. 

44 The Cyclopaedia, when complete, will form a valuable work of reference, as 
well as a most entertaining and instructive library. It is an essential principle 
in every part of it, that it should be clear and easily understood, and that an 
attempt should everywhere be made to unite accurate information with an 
agreeable manner of conveying it. It is an experiment to try how much science 
may be taught with little crabbed or technical language, and how far the philo- 
sophical and poetical qualities of history may be preserved in its more condensed 
state. It possesses also the most indispensable of all the qualities of a work 
intended for general instruction— that of cheapness. Whatever the plan might 
be, it was evident that the grand difficulty of Dr. Lardner was to unite a body 
of writers in its execution, whose character or works afforded the most probable 
hope that they were fitted for a task of which the peculiarity, the novelty, and 
even the prevalent relish for such writings greatly enhance the difficulty. We 
do not believe, that in the list of contributors, there is one name of which the 
enlightened part of the public would desire the exclusion. 

44 In science, the list is not less promising. The names of the President, Vice- 
Presidents, and most distinguished Fellows of the Royal Society, are contained 
in it. A treatise on astronomy, byHerschel; on optics, by Brewster; and on 
mechanics, by Lardner ; need be only recommended by the subjects and the wri 
ters. An eminent Prelate, of the first rank in science, has undertaken a noble 
subject which happily combines philosophy with religion. Twelve of the most 
distinguished naturalists of the age, Fellows of the Linnaean and Zoological 
Societies, are preparing a course of natural history. Others not less eminent in 
literature and science, whose names it is not needful yet to mention, have shown 
symptoms of an ambition to take a place among such fellow-laborers."— Times 

41 The topics, as may be supposed, are both judiciously selected and treated 
with ability. To general readers, and as part of a family library, the volumes 
already published possess great recommendations. For the external beauties of 
good printing and paper they merit equal commendation." — Bait. American. 

44 The uniform neatness of these volumes, their very moderate price, and the 
quantity of information which they contain, drawn from the best and most 
attractive sources, have given them deserved celebrity, and no one who desires 
to possess such information, should hesitate a moment to add them to his 
library." — Fed. Gazette. 

44 This excellent work continues to increase in public favor, and to receive 
fresh accessions of force to its corps of contributors " — Lit. Gazette. 

44 Its plan and arrangement are entitled to our best commendations." — Gent. 
Mag. 



LARDNER'S CABINET CYCLOP JCDIA. 



It is not easy to devise a cure for such a state of things (the de- 
clining TASTE FOR SCIENCE;) BUT THE MOST OBVIOUS REMEDY IS TO PROVIDE 
THE EDUCATED CLASSES WITH A SERIES OF WORKS ON POPULAR AND PRACTI- 
CAL SCIENCE, FREED FROM MATHEMATICAL SYMBOLS AND TECHNICAL TERMS, 
WRITTEN IN SIMPLE AND PERSPICUOUS LANGUAGE, AND ILLUSTRATED BY FACTS 
A1»D EXPERIMENTS, WHICH ARE LEVEL TO THE CAPACITY OF ORDINARY MINDS. 1 ' 

Quarterly Review. 



PRELIMINARY DISCOURSE ON THE OBJECTS, ADVAN- 
TAGES, AND PLEASURES OP THE STUDY OF NATU- 
RAL PHILOSOPHY. By J, T. W. Herschel, A. M. late Fel- 
low of St. John's College, Cambridge. 

44 Without disparaging any other of the many interesting and instructive vol- 
umes issued in the form of cabinet and family libraries, it is, perhaps, not too 
much to place at the head of the list, for extent and variety of condensed infor- 
mation, Mr. Herchel's discourse of Natural Philosophy in Dr. Lardner's Cyclo- 
paedia." — Christian .Observer. 

' The finest work of philosophical genius which this age has seen." — Mackin- 
tosh" s England. 

" By far the most delightful book to which the existing competition between 
literary rivals of great talent and enterprise has given rise" — Monthly Review. 

44 Mr. Herschel's delightful volume. * * * We find scattered through the 
work instances of vivid and happy illustration, where the fancy is usefully called 
into action, so as sometimes to remind us of the splendid pictures which crowd 
upon us in the style of Bacon." — Quarterly Review. 

4 It is the most exciting volume of the kind we ever met with."— Monthly 
Magazine. 

44 One of the most instructive and delightful books we have ever perused."— 
XJ. S. Journal. 



A TREATISE ON MECHANICS. By Capt. Kater, and the 
Rev* Dionysius Lardner* With numerous engravings* 

* A work which contains an uncommon amount of useful information, ex- 
hibited in a plain and very intelligible form." — Olmsted's Nat. Philosophy. 

"This volume has been lately published in England, as a part of Dr. Lardner's 
Cabinet Cyclopaedia, and has received the unsolicited approbation of the most 
eminent men of science, and the most discriminating journals and reviews, in 
the British metropolis. — It is written in a popular and intelligible style, entirely 
free from mathematical symbols, and disencumbered as far as possible of tech- 
nical phrases." — Boston Traveller. 

■' Admirable in development and clear in principles, and especially felicitous in 
illustration from familiar subjects."— Monthly Mag. 

11 Though replete with philosophical information of the highest order in me- 
chanics, adapted to ordinary capacities in a way to render it at once intelligible 
and popular."— Lit. Gazette. 

" A work of great merit, full of valuable information, not only to the practical 
mechanic, but to the man of science." — JV*. Y. Courier and Enquirer. 



A TREATISE ON HYDROSTATICS AND PNEUMATICS. 
By the Rev* D* Lardner* With numerous engravings* 

44 It fully sustairs the favorable opinion we have already expressed as to this 
valuable compendium of modern science." — Lit. Gazette. 

44 Dr. Lardner has made a good use of his acquaintance with the familiar facts 
which illustrate the principles of science." — Monthly Magazine. 

*' It is written with a full knowledge of the subject, and in a popular style, 
abounding in practical illustrations of the abstruse operations of these impor- 
tant sciences." — XJ. <S. Journal. 



LARDNER S CABINET CYCLOPAEDIA. 



HISTORY of the RISE, PROGRESS, and PRESENT 
STATE of the SILK MANUFACTURE ; with numerous 
engravings. 

" The volume treats of everything relating to the fabric, embracing many 
historical observations and interesting facts in natural history, with practical 
directions of the minutest kind, for the guidance of those engaged in the pro- 
duction or the manufacture of silk. These details, with the accompanying en-J 
gravings of machinery, must prove particularly valuable to those who wish to 
attain an accurate knowledge of a very important art, on the history of which 
alone the general reader will find much to interest him in the first part of the 
volume."— JV. ¥. American. 

" Tt contains abundant information in every department of this interesting 1 
branch of human industry— in the history, culture, and manufacture of silk " 
— Monthly Magazine. 

" There is a great deal of curious information in this little volume. "-Z.i£. Oaz, 

HISTORY of the ITALIAN REPUBLICS ; being a View of 

the Rise, Progress, and Fall of Italian Freedom. By J. C. L. 

De Sismondi. 

" The excellencies, defects, and fortunes of the governments of the Italian 
commonwealths form a body of the most valuable materials for political phi- 
losophy. It is time that they should be accessible to the American people, as 
they are about to be rendered in Sismondi's masterly abridgment. He has done 
for his large work, what Irving accomplished so well for his Life of Columbus. 
—Nat. Gazette. 

HISTORY of the RISE, PROGRESS, and PRESENT 
STATE of the MANUFACTURES of PORCELAIN 
and GLASS. With numerous wood cuts. 

HISTORY of the RISE, PROGRESS, and PRESENT 
STATE of the IRON and STEEL MANUFACTURE. 
(In press.) 

"This volume appears to contain all useful information on the subject of 
which it treats."— Lit. Gazette. 

" These volumes are full of interest. * * * The present volume embraces the 
manufactures of Iron and Steel only, and describes the present state of the 
more important branches of both. Bridges, cannon, anchors, chains, screws, 
figure in the first department — files, edge-tools, and saws, the latter; and the 
history of all forms not the least interesting portion." — Mechanic's Magazine. 

BIOGRAPHY of BRITISH STATESMEN ; containing the 
Lives of Sir Thomas More, by Sir James Mackintosh ; Car- 
dinal Wolsey, Archbishop Cranmer, and Lord Burleigh. 

"A very delightful volume, and on a subject likely to increase in interest as 

Iit proceeds. * * * We cordially commend the work both for its design and ex- 
ecution." — London Lit. Gazette. 

" The Life of More, being from the pen of Sir James Mackintosh, engaged 
and fully rewarded our attention. It is a rich theme, and has been treated 
with the lofty philosophical spirit and literary skill which distinguish the ! 
writings of Sir James." — Nat. Gazette. 

" We" are certain, that no one can rise from the perusal of the work, without 
having his understanding enlarged, and the best affections of his heart im- 
proved." — Album. 

"A most interesting and valuable volume." — Gent. Magazine. 

ELEMENTS of OPTICS. By David Brewster. 18mo. (In press.) j 

"The author has given proof of his well-known industry, and extensive ac- 
quaintance with the results of science in every part of Europe."— Month. Mag. 

" The subject is, as might be expected, ably treated, and clearly illustrated." 
— U. S. Jour. 



LARDNER'S CABINET CYCLOPAEDIA. 

HISTORY OF ENGLAND. By Sir James Mackintosh. Ill 8 
Vols. Vols. 1 and 2 published. 

" In the first volume of Sir James Mackintosh's History of England, we find 
enough to warrant the anticipations of the public, that a calm and luminous 
philosophy will diffuse itself over the long narrative of our British History."— 
Edinburgh Review. 

" In this volume Sir James Mackintosh fully developes those great powers, for 
the possession of which the public have long given him credit. The result is the 
ablest commentary that has yet appeared in our language upon some of the most 
important circumstances of English History." — Atlas. 

" Worthy in the method, style, and reflections, of the author's high reputation. 
We were particularly pleased with his high vein of philosophical sentiment, and 
his occasional survey of contemporary annals." — National Gazette. 

"If talents of the highest order, long experience in politics, and years of ap- 
plication to the study of history and the collection of information, can command 
superiority in ahistorian, Sir James Mackintosh may, without reading this work, 
be said to have produced the best history of this country. A perusal of the 
work will prove that those who anticipated a superior production, have not reck- 
oned in vain on the high qualifications of the author." — Courier. 

" Our anticipations of this volume were certainly very highly raised, and un- 
like such anticipations in general, they have not been disappointed. A philo- 
sophical spirit, a nervous style, and a full knowledge of the subject, acquired by 
considerable research into the works of preceding chroniclers and historians, 
eminently distinguish this popular abridgment, and cannot fail to recommend it 
to universal approbation. In continuing his work as he has begun, Sir James 
Mackintosh will confer a great benefit on his country." — Lond. Lit. Gazette. 

" Of its general merits, and its permanent value, it is impossible to speak, 
without the highest commendation, and after a careful and attentive perusal of 
the two volumes which have been published, we are enabled to declare that, so 
far, Sir James Mackintosh has performed the duty to which he was assigned, 
with all the ability that was to be expected from his great previous attainments, 
his laborious industry in investigation, his excellent judgment, his superior tal- 
ents, and his honorable principles." — Inquirer. 

" We shall probably extract the whole of his view of the reformation, merely 
to show how that important topic has been handled by so able and philosophical 
a writer, professing Protestantism. — National Gazette. 

1 The talents of Sir James Mackintosh are so justly and deeply respected, that 
a strong interest is necessarily excited with regard to any work which such a 
distinguished writer may think fit to undertake. In the present instance, as in 
all others, our expectations are fully gratified." — Gentleman's Magazine. 

The second volume of the History of England, forming the sixth of Carey &. 
Lea's Cabinet Cyclopaedia, has been sent abroad, and entirely sustains the repu- 
tation of its predecessors. The various factions and dissensions, the important 
trials and battles, which render this period so conspicuous in the page of history, 
are all related with great clearness and masterly power."— Boston Traveller. 



HISTORY OF SCOTLAND. By Sir Walter Scott. In 2 Vols. 

" The History of Scotland, by Sir Walter Scott, we do not hesitate to declare, 
will be, if possible, more extensively read, than the most popular work of fiction, 
by the same prolific author, and for this obvious reason : it combines much of the 
brilliant coloring of the Ivanhoe pictures of bygone manners, and all the grace- 
ful facility of style and picturesqueness of description of his other charming ro- 
mances, with a minute fidelity to the facts of history, and a searching scrutiny 
into their authenticity and relative value, which might put to the blush Mr. 
Humfi and other professed historians. Such is the magic charm of Sir Walter 
Scott's pen, it has only to touch the simplest incident ofevery-day life, and it starts 
up invested with all the interest of a scene of romance ; and yet such is his fideli- 
ty to the text of nature, that the knights, and serfs, and collared fools with whom 
his inventive genius has peopled so many volumes, are regarded by us as not 
mere creations of fancy, but as real flesh and blood existences, with all the vir- 
tues, feelings and errors of common-place humanity." — Lit. Gazette. 



LARDNER S CABINET CYCLOPAEDIA. 



OF THE MANY WORKS WHICH HAVE DEEN LATELY PUBLISHED IN IMITATION, OR 
ON THE PLAN ADOPTED BY THE SOCIETY FOR THE DIFFUSION OF USEFUL KNOW- 
LEDGE, DR. LARDNER'S CYCLOPAEDIA IS BY MUCH THE MOST VALUABLE, AND 
THE MOST RECOMMENDED BY DISTINGUISHED ASSISTANCE, SCIENTIFIC AND LIT- 

etary." — Edinburgh Review. 



HISTORY OF FRANCE. By Eyre Evans Crowe. In 3 vols. 

HISTORY OF FRANCE, from the Restoration of the Bour- 
bons, to the Revolution of 1830. By T. B. Macaulay, Esq. 
M. P. Nearly ready. 

" The style is concise and clear; and events are summed up with much vigor 
and originality." — Lit. Oazette. 

" His history of France is worthy to figure with the works of his associates, 
the best of their day, Scott and Mackintosh."— Monthly Mag. 

" For such a task Mr. Crowe is eminently qualified. At a glance, as it were, 
his eye takes in the theatre of centuries. His style is neat, clear, and pithy ; and 
his power of condensation enables him to say much, and effectively, in a few 
words, to present a distinct and perfect picture in a narrowly circumscribed 
space." — La Belle Assemblee. 

"The style is neat and condensed ; the thoughts and conclusions sound and 
just. The necessary conciseness of the narrative is unaccompanied by any 
baldness ; on the contrary, it is spirited and engaging."— Bait. American. 

"To compress the history of a great nation, during a period of thirteen hun- 
dred years, into two volumes, and to preserve sufficient distinctness as well as 
interest in the narrative, to enable and induce the reader to possess himself 
clearly of all the leading incidents, is a task by no means easily executed. It 
has, nevertheless, been well accomplished in this instance."— JV*. Y. American. 

"Written with spirit and taste."— U. S. Oazette. 

"Could we but persuade our young friends to give these volumes a careful 
perusal, we should feel assured of their grateful acknowledgments of profit and 
pleasure."— JV*. Y. Mirror. 

" At once concise and entertaining." — Saturday Bulletin. 



THE HISTORY OF THE NETHERLANDS, to the Battle of 
Waterloo. By T. C. Grattan. 

" It is but justice to Mr. Grattan to say that he has executed his laborious 
task with much industry and proportionate effect. Undisfigured by pompous 
nothingness, and without any of the affectation of philosophical profundity, his 
style is simple, light, and fresh— perspicuous, smooth, and harmonious." — La 
Belle Assemblee. 

" Never did work appear at a more fortunate period. The volume before us 
is a compressed but clear and impartial narrative." — Lit. Oaz. 

" A long residence in the country, and a ready access to libraries and archives, 
have furnished Mr Grattan with materials which he has arranged with skill, 
and out of which he has produced a most interesting volume." — Gent. Mag. 



BIOGRAPHY OF BRITISH STATESMEN; containing the 
Iiives of Sir Thomas More, Cardinal Wolsey, Archbishop 
Cranmer, and Lord Burleigh. 

" A very delightful volume, and on a subject likely to increase in interest as it 
proceeds. * * * We cordially commend the work both for its design and 
execution." —Lond. Lit. Gazette. 



CABINET OF AMERICAN HISTORY. 



Volumes published* 

I. II. HISTORY of the SPANISH DISCOVERIES prior to the year 1520. 

To t>e succeeded l>y 

III. IV. V. HISTORY of ANAHUAC, or MEXICO, from its discovery 

to the present time. In 3 vols. 
VI. VII. HISTORY of PERU. In 2 vols. 
VIII. IX. HISTORY of BRAZIL. In 2 vols. &c. &c. 



Under this comprehensive title, it is proposed to publish a General His- 
tory of America, divided into parts making together a continuous whole; 
yet each, having an integral form, adapted for separate publication. Each 
portion will be brought down to the period at which it shall be written, 
and will contain a popular description of the geology, climate and produc- 
tions, and the civil history of the country to which it relates. 

No work of this general nature has been published in the English lan- 
guage. The work of Dr. Robertson is rather a philosophical essay on 
American history, than an historical narrative ; and though originally de- 
signed to embrace the whole of the American continent, it remains un- 
finished. It is written also, with a bias unfavorable to America and its 
productions, is incorrect in many important particulars, and is too much 
abstracted for popular use. 

This void in literature might have been properly filled by the writers of 
Spain, Portugal, France, or England, but has been supplied for Europe, in 
a measure, by an Italian, the Cavalier Campagnoni, of whose meritorious 
labor much use will be made in the proposed enterprise. 

The volumes herewith presented, may be deemed introductory to the 
whole work, since they narrate the history of the discovery of the three 
great portions of America. In the prosecution of the subject, the existing 
political divisions will be pursued and connected with former ones, by 
proper explanations ; and where due regard for unity does not forbid, the 
chronological order will be preserved. Thus, the next succeeding part of 
the work, now advanced in preparation, will contain the history of Anahuac, 
or Mexico : including its ancient annals, an account of its subjugation, and 
the policy of its conquerors, of its late revolutions, and of its present con- 
stituent states. In the same manner will be treated Central America, Peru, 
Chili, Bolivia, the United Provinces of La Plata, Brazil and Colombia. Due 
attention will also be given to the independent Indian nations of South 
America 

The history of the remainder of the country will be embraced by the 
following divisions : — 1. Russian ; 2. British ; 3. Spanish ; 4. French ; 5. 
Danish ; 6. Dutch America ; and 7, the United States and their dependen- 
cies. In treating the last division, a separate volume will be appropriated 
to each State and Territory, the history of which may require it, and " The 
History of the United States" will be confined to the events of the Revolu- 
tion and the operations of the general government. 

A survey having been thus made of the whole Western Hemisphere, the 
concluding volume will contain the history of the Indian races, particularly 
those of the northern part of the continent, with a critical examination of 
the theories relating to the original peopling of America. 

The general title of the work is sufficiently comprehensive to include a 
biography of distinguished Americans, and others connected with Ameri- 
can history ; and should the public support warrant it, " An American Bi- 
ography " may also be published under it, in a cheap and popular form. 



CABINET LIBRARY. 



No. 1.— NARRATIVE OF THE LATE WAR IN GER- 
MANY AND FRANCE. By the Marquess of London- 
derry. With a Map. 

No. 2.— JOURNAL of a NATURALIST, with plates. 

No. 3.— AUTOBIOGRAPHY of SIR WALTER SCOTT. 
With a portrait. 

No. 4.— MEMOIRS of SIR WALTER RALEGH. By Mrs. 
A. T. Thomson. 

No. 5.— LIFE of BELISARIUS. By Lord Mahon. 

No. 6.— MILITARY MEMOIRS of the DUKE of WEL- 
LINGTON. By Capt. Moyle Sherer. With a portrait. 

No. 7.— LETTERS to a YOUNG NATURALIST on the 
STUDY of NATURE and NATURAL THEOLOGY. By 
J. L. Drummond, M. D. With numerous engravings. 

IN PREPARATION. 

LIFE of PETRARCH. By Thomas Moore. 
GLEANINGS in NATURAL HISTORY, being a Companion 
to the Journal of a Naturalist. 

"The Cabinet Library bids fair to be a series of great value, and is recom- 
mended to public and private libraries, to professional men, and miscellaneous 
readers generally. It is beautifully printed, and furnished at a price which will 
place it within the reach of all classes of society." — American Traveller. 

"The series of instructive, and, in their original form, expensive works, 
which these enterprising publishers are now issuing under the title of the 
" Cabinet Library," is a fountain of useful, and almost universal knowledge ; 
the advantages of which, in forming the opinions, tastes and manners of that 
portion of society, to which this varied information is yet new, cannot be too 
highly estimated." — National Journal. 

" Messrs. Carey and Lea have commenced a series of publications under the 
above title, which are to, appear monthly, and which seem likely, from the spe- 
cimen before us, to acquire a high degree of popularity, and to afford a mass of 
various information and rich entertainment, at once eminently useful and 
strongly attractive. The mechanical execution is fine, the paper and typography 
excellent." — Nashville Banner. 



MEMOIRS OF THE LIFE OF SIR WALTER RAIiEGH, 
with some Account of the Period in which he lived* By 
MRS. A, T. THOMSON. With a Portrait. 

" Such is the outline of a life, which, in Mrs. Thomson's hands, is a mine of 
interest; from the first page to the last the attention is roused and sustained, 
ai;d while we approve the manner, we still more applaud the spirit in which it 
is executed." — Literary Gazette. 



CABINET UBRART. 



JOURNAL. OF A NATURAMST. With Plates* 



-Plants, trees, and stones we note; 



Birds, insects, beasts, and rural things. 

"We again most strongly recommend this little unpretending volume to the 
attention of every lover of nature, and more particularly of our country read- 
ers It will induce them, we are sure, to examine more closely than they have 
been accustomed to do, into the objects of animated nature, and such examina- 
tion will prove one of the most innocent, and the most satisfactory sources of 
gratification and amusement. It is a book that ought to find its way into every 
rural drawing-room in the kingdom, and one that may safely be placed in every 
lady's boudoir, be her rank and station in life what they may." — Quarterly Re- 
view, No. LXXVIII. 

" We think that there are few readers who will not be delighted (we are cer- 
tain all will be instructed) by the ' Journal of a Naturalist.' "—Monthly Review 

" This is a most delightful book on the most delightful of all studies. We are 
acquainted with no previous work which bears any resemblance to this, except 
' White's History of Selborne,' the most fascinating piece of rural writing and 
sound English philosophy that ever issued from the press." — Athcnaum. 

"The author of the volume now before us, has produced one of the most 
charming volumes we remember to have seen for a long time."— New Month- 
ly Magazine, June, 1829. 

" A delightful volume— perhaps the most so — nor less instructive and amusing 
— given to Natural History since White's Selborne." — Blackwood's Magazine. 

" The Journal of a Naturalist, being the second number of Carey and Lea's 
beautiful edition of the Cabinet Library, is the best treatise on subjects con- 
nected with this train of thought, that we have for a long time perused, and we 
are not at all surprised that it should have received so high and flattering enco- 
miums from the English press generally." — Boston Traveller. 

"Furnishing an interesting and familiar account of the various objects of 
animated nature, but calculated to afford both instruction and entertainment." 
— Nashville Banner. 

" One of the most agreeable works of its kind in the language."— Courier de 
la Louisiane. 

"It abounds with numerous and curious facts, pleasing illustrations of the 
secret operations and economy of nature, and satisfactory displays of the power, 
wisdom and goodness, of the great Creator.' 1 — Philad. Album. 



THE MARQUESS OF LONDONDERRY'S NARRATIVE OF 
THE LATE WAR IN GERMANY AND FRANCE. Witli a 
Map. 

u No history of the events to which it relates can be correct without reference 
to its statements." — Literary Gazette. 

" The events detailed in this volume cannot fail to excite an intense interest." 
— Dublin Literary Gazette. 

"The only connected and well authenticated account we have of the spirit- 
stirring scenes which preceded the fall of Napoleon. It introduces us into the 
cabinets and presence of the allied monarchs. We observe the secret policy of 
each individual : we see the course pursued by the wily Bernadotte, the tempo- 
rizing Metternich, and the ambitious Alexander, The work deserves a place in 
every historical library." — Globe. 

" We hail with pleasure the appearance of the first volume of the Cabinet 
Library." "The author had singular facilities for obtaining the materials of 
his work, and he has introduced us to the movements and measures of cabinets 
which have hitherto been hidden from the world." — American Traveller. 

"It may be regarded as the most authentic of all the publications which pro- 
fess to detail ihe events of the important campaigns, terminating with that 
which secured the capture of the French metropolis." — Nat. Journal. 

" It is in fact the only authentic account of the memorable events to which 
it refers." — Nashville Banner. 

" The work deserves a place in every library."— Philadelphia Album. 



SCOTT AND COOPER. 



BY SIR WALTER SCOTT. 



COUNT ROBERT OF PARIS, a Tale of the Lower Empire. 

By the Author of Waverley. In 3 vols. 

"The reader will at once perceive that the subject, the characters and the 
scenes of action, could not have been better selected for the display of the vari- 
ous and unequalled powers of the author. All that is glorious in arts and splen- 
did in arms— the glitter of armor, the pomp of war, and the splendor of chivalry 
—the gorgeous scenery of the Bosphorus — the ruins of Byzantium — the magnifi- 
cence of the Grecian capital, and the richness and voluptuousness of the impe- 
rial court, will rise before the reader in a succession of beautiful and dazzling 
images." — Commercial Advertiser. 

AUTOBIOGRAPHY OF SIR WALTER SCOTT. With a 

Portrait 
HISTORY OF SCOTLAND. In 2 vols. 

" The History of Scotland, by Sir Walter Scott, we do not hesitate to declare, 
will be, if possible, more extensively read, than the most popular work of fiction, 
by the same prolific author, and for this obvious reason : it combines much of the 
brilliant coloring of the Ivanhoe pictures of bygone manners, and all the grace- 
ful facility of style and picturesqueness of description of his other charming ro- 
mances, with a minute fidelity to the facts of history, and a searching scrutiny 
into their authenticity and relative value, which might put to the blush Mr. 
Hume and other professed historians. Such is the magic charm of Sir Walter 
Scott's pen, it has only to touch the simplest incident ofevery-day life, and it starts 
up invested with all the interest of a scene of romance ; and yet such is his fideli- 
ty to the text of nature, that the knights, and serfs, and collared fools with whom 
his inventive genius has peopled so many volumes, are regarded by us as not 
mere creations of fancy, but as real flesh and blood existences, with all the vir- 
tues, feelings and errors of common-place humanity." — Lit. Gazette. 

TALES of a GRANDFATHER, being a series from French 
History. By the Author of Waverley. 



BY MR. COOPER. 



THE BRAVO. By the Author of the Spy, Pilot, &c. In 2 vols. 

The WATER- WITCH, or the SKIMMER of the SEAS. 
In 2 vols. 

" We have no hesitation in classing this among the most powerful of the ro- 
mances of our countryman." — U. States Gazette. 

"We could not break from the volumes, and may predict that they will excite 
the same interest in the minds of almost every reader. The concluding chapters 
produce intense emotion." — National Gazette. 

New Editions of the following Works by the same Author. 

NOTIONS OF THE AMERICANS, by a Travelling Bachelor, 

2 vols. 12mo. 
The WEPT OF WISH-TON-WISH, 2 vols. 12mo. 
The RED ROVER, 2 vols. 12mo. 
The SPY, 2 vols. 12mo. 
The PIONEERS, 2 vols. 12mo. 
The PILOT, a Tale of the Sea, 2 vols. 12mo. 
LIONEL LINCOLN, or the LEAGUER of BOSTON, 2 vols. 
The LAST of the MOHICANS, 2 vols. 12mo. 
The PRAIRIE, 2 vols. 12mo. 



MISCELLANEOUS. 

A MEMOIR OF SEBASTIAN CABOT, with a Review of the 
History of Maritime Discovery. Illustrated hy Documents 
from the Rolls, now first published* 

" Put forth in the most unpretending manner, and without a name, this work 
is of paramount importance to the subjects of which it treats."— Lit. Oazette. 
" The author has corrected many grave errors, and in general given us a clearer 
insight into transactions of considerable national interest." — lb. " Will it not," 
says the author, with just astonishment, " be deemed almost incredible, that the 
very instrument in the Records of England, which recites the Great Discovery, 
and plainly contemplates a scheme of Colonization, should, up to this moment, 
have been treated by her own writers as that which first gave permission to go 
forth and explore ?"— lb. "We must return to investigate several collateral 
matters which we think deserving of more space than we can this week bestow. 
Meanwhile we recommend the work as one of great value and interest."— Jb. 

" The general reader, as well as the navigator and the curious, will derive 
pleasure and information from this well-written production." — Courier. 

" A specimen of honest inquiry. It is quite frightful to think of the number of 
the inaccuracies it exposes : we shall cease to have confidence in books." " The 
investigation of truth is not the fashion of these times. But every sincere in- 
quirer after historical accuracy ought to purchase the book as a curiosity: more 
false assertions and inaccurate statements were never exposed in the same com- 
pass. It has given us a lesson we shall never forget, and hope to profit by."— Sped. 



HISTORY OF THE NORTHMEN, OR NORMANS AND 
DANES ; from the earliest times to the Conquest of Eng- 
land hy William of Normandy. By Henry Wheat .on, Mem- 
her of the Scandinavian and Icelandic Literary Societies 
of Copenhagen. 

This work embraces the great leading features of Scandinavian history, com- 
mencing with the heroic age, and advancing from the earliest dawn of civiliza- 
tion to the introduction of Christianity into the North— its long and bloody 
strife with Paganism— the discovery and colonization of Iceland, Greenland, 
and North America, by the Norwegian navigators, before the time of Columbus 
— the military and maritime expeditions of the Northmen— their early inter- 
course of commerce and war with Constantinople and the Eastern empire — the 
establishment of a Norman state in France, under Rollo, and the subjugation of 
England, first by the Danes, under Canute the Great, and subsequently by the 
Normans, under Duke William, the founder of the English monarchy. It also 
contains an account of the mythology and literature of the ancient North — the 
Icelandic language prevailing all over the Scandinavian countries until the 
formation of the present living tongues of Sweden and Denmark — an analysis 
of the Eddas, Sagas, and various chronicles and songs relating to the Northern 
deities and heroes, constituting the original materials from which the work has 
been principally composed. It is intended to illustrate the history of France 
and England during the middle ages, and at the same time to serve as an intro- 
duction to the modern history of Denmark, Norway, and Sweden. 



AN HISTORICAL INQUIRY INTO THE PRODUCTION 
AND CONSUMPTION OF THE PRECIOUS METAIiS, 
from the Earliest Ages, and into the Influence of their In- 
crease or Diminution on the Prices of Commodities* By 
William Jacoh, Esq* F. R* S* In 8vo* 

" Mr. Jacob's Historical Inquiry into the Production and Consumption of the 
Precious Metals is one of the most curious and important works which has 
lately issued from the press. The influence of the precious metals on the indus- 
try of mankind is acknowledged to be great ; though, perhaps, the notions re- 
specting the precise mode of its operation were obscure, and undoubtedly the 
history of its effects had never been traced with accuracy and ingenuity. Mr. 
Huskisson, who had maintained a friendship with Mr. Jacob for more than five- 
and-twenty years, first put the author on the investigation; it is one of the minor 
obligations which the country owes to that enlightened statesman." — Spectator. 
41 It was written at the suggestion of the late Mr. Huskisson, and displays 
the fruits of much industry and research, guided by a sound judgment, and em- 
bodying more learning than is usually brought to bear on statistical or eco- 
nomical subjects. We recommend the book to general attention." — Times. 



EDUCATION. 



LESSONS on THINGS, intended to improve Children in the 
Practice of Observation, Reflection, and Description, on the Sys- 
tem of Pestalozzi, edited by John Frost, A. M. 

The publishers request the attention of Teachers, School Com- 
mittees, and all who are desirous of improving the methods of in- 
struction, to this work, which is on a plan hitherto unattempted 
by any school-book in this country, and which has been attended 
with extraordinary success in England. 

The following remarks on the work are extracted from the 
" Quarterly Journal of Education." 

" This little volume is a ' corrected and re-corrected' edition of lessons actual- 
ly given to children, and, therefore, possesses a value to which no book made in 
the closet can lay claim, being the result of actual experiment. The work con- 
sists of a number of lessons, divided into five series: beginning with subjects 
the most easy and elementary, it gradually increases in difficulty, each succes- 
sive step being adapted to the mind of the child as it acquires fresh stores of 
knowledge. 

" Every part of these lessons is interesting to the child, both on account of the 
active operation into which his own mind is necessarily called by the manner in 
which the lessons are given ; and also by the attractive nature of many of the 
materials wbich form the subject of the lessons. In the first and most elementa- 
ry series, the pupil is simply taught to make a right use of his organs of sense, 
and to exercise his judgment so far only as relates to the objects about him ; and 
accordingly the matter brought before him at this stage, is such that its obvious 
properties can be discovered and described by a child who has acquired a tolera- 
ble knowledge of his mother tongue." 

GREEK and ENGLISH LEXICON. By D. Donnegan. 
Abridged for the use of Schools. In 1 vol. royal 18mo. con- 
taining above 600 pages. 

This work is printing on a handsome distinct type, and will contain as 
much matter as many of the larger lexicons ; but owing to the form in 
which it is printed, will be sold at such price as to be within the reach of 
all students. It will offer more advantages to the young student than any 
other lexicon now in use. The vocabulary is more extensive and com- 
plete — comprising not only words found in the classics, but also such as are 
found in the writings of Hippocrates and the Greek Physicians. The 
meanings attached to words by the several writers are also given. 

Words are given in alphabetical order in every poetical and dialectic 
variety. 

The conjugation of verbs and flection of nouns are more complete than 
in other lexicons ; — the meanings of words fuller and more correct — there 
being first a primary and then a secondary meaning, each distinguished 
from the metaphorical and idiomatical. Phrases are also given when they 
note any peculiarity in signification. The etymology of words is only 
omitted where it is confused or disputed. There is nothing left out which 
the young student would find necessary in studying the Classics, and 
which would enable him to understand the true meaning of a word. In 
short, in this work the essential advantages of a good Dictionary are com- 
bined with those of a good Grammar — advantages not found in any Greek 
and English Lexicon now used. 



WASHm&TOlf IRVING-. 



VOYAGES and ADVENTURES of the COMPANIONS of 
COLUMBUS. By Washington Irving, Author of the Life 
of Columbus, &c. 1 vol. 8vo. 

"Of the main work we may repeat that it possesses the value of important 
history and the magnetism of romantic adventure. It sustains in every respect 
the reputation of Irving." ■' We may hope that the gifted author will treat in like 
manner the enterprises and exploits of Pizarro and Cortes ; and thus complete a 
series of elegant recitals, which will contribute to the especial gratification of 
Americans, and form an imperishable fund of delightful instruction for all ages 
and countries." — Nat Gazette. 

" As he leads us from one savage tribe to another, as he paints successive 
scenes of heroism, perseverance and self-denial, as he wanders among the mag- 
nificent scenes of nature, as he relates with scrupulous fidelity the errors, and 
the crimes, even of those whose lives are for the most part marked with traits 
to command admiration, and perhaps esteem — everywhere we find him the same 
undeviating, but beautiful moralist, gathering from every incident some lesson 
to present in striking language to the reason and the heart." — Jim. Quarterly 
Review. 

"This is a delightful volume; for the preface truly says that the expeditions 
narrated and springing out of the voyages of Columbus may be compared with 
attempts of adventurous knights-errant to achieve the enterprise left unfinished 
by some illustrious predecessors. Washington living's name is a pledge how 
well their stories will be told : and we only regret that we must of necessity de- 
fer our extracts for a week." — London Lit. Gazette 

A CHRONICLE of the CONQUEST of GRENADA. By 
Washington Irving, Esq. In 2 vols. 

"On the whole, this work will sustain the high fame of Washington Irving. 
It fills a blank in the historical library which ought not to have remained so 
long a blank. The language throughout is at once chaste and animated ; and 
the narrative may be said, like Spenser's Fairy Queen, to present one long gal- 
lery of splendid pictures." — Lond. Lit. Gazette. 

"Collecting his materials from various historians, and adopting in some 
degree the tone and manner of a monkish chronicler, he has embodied them in 
a narrative which in manner reminds us of the rich and storied pages of Frois- 
sart. He dwells on the feats of chivalry performed by the Christian Knights, 
with all the ardor which might be expected from a priest, who mixed, according 
to the usage of the times, not only in the palaces of courtly nobles, and their gay 
festivals, as an honored and welcome guest, but who was their companion in 
the camp, and their spiritual and indeed bodily comforter and assistant in the 
field of battle. — Jim. Quarterly Review. 



New Editions of the following Works by the same Author. 

The SKETCH BOOK, 2 vols. 12mo. 

KNICKERBOCKER'S HISTORY of NEW YORK, revised 
and corrected. 2 vols. 

BRACEBRIDGE HALL, or the HUMORISTS, 2 vols. 12mo. 

TALES of a TRAVELLER, 2 vols. 12mo. 



CLASSICAL LITERATURE. 






INTRODUCTION to the STUDY of the GREEK CLASSIC 
POETS, for the use of Young Persons at School or College. 

Contents. — General Introduction; Homeric Questions; 
Life of Homer ; Iliad ; Odyssey ; Margites ; Batrachomyo- 
machia ; Hymns ; Hesiod. By Henry Nelson Coleridge. 

"We have been highly pleased with this little volume. This work supplies a 
want which we have often painfully felt, and affords a manual which we should 
gladly see placed in the hands of every embryo under-graduate. We look for- 
ward to the next portion of this work with very eager and impatient ex- 
pectation."— British Critic. 

" Mr. Coleridge's work not only deserves the praise of clear, eloquent and 
scholar like exposition of the preliminary matter, which is necessary in order to 
understand and enter into the character of the great Poet of antiquity; but it 
has likewise the more rare merit of being admirably adapted for its acknow- 
ledged purpose. It is written in that fresh and ardent spirit, which to the con- 
genial mind of youth, will convey instruction in the most effective manner, by 
awakening the desire of it; and by enlisting the lively and buoyant feelings in 
the cause of useful and improving study; while, by its pregnant brevity, it is 
more likely to stimulate than to supersede more profound and extensive research. 
If then, as it is avowedly intended for the use of the younger readers of Homer, 
and, as it is impossible not to discover, with a more particular view to the great 
school to which the author owes his education, we shall be much mistaken if it 
does not become as popular as it will be useful in that celebrated establish- 
ment." — Quarterly Review. 

" We sincerely hope that Mr. Coleridge will favor us with a continuation of 
this work, which he promises. — Oent. Mag. 

"The author of this elegant volume has collected a vast mass of valuable in- 
formation. To the higher classes of the public schools, and young men of uni- 
versities, this volume will be especially valuable; as it will afford an agreeable 
relief of light reading to more grave studies, at once instructive and entertain- 
ing." — Wesley an Methodist Magazine. 

ATLAS OF ANCIENT GEOGRAPHY, consisting of 21 Col- 
ored Maps, with a complete Accentuated Index. By Samuel 
Butler, D. D., F. R. S. &c. Archdeacon of Derby. 

By the same Author. 

GEOGRAPHIA CLASSICA : a Sketch of Ancient Geography, 
for the Use of Schools. In 8vo. 

Extract of a Letter from Professor Stuart of Andover. 

11 1 have used Butler's Atlas Classica for 12 or 14 years, and prefer it on the 
score of convenience and correctness to any atlas within the compass of my 
knowledge. It is evidently a work of much care and taste, and most happily 
adapted to classical readers and indeed all others, who consult the history of past 
ages. I have long cherished a strong desire to see the work brought forward in 
this country, and I am exceedingly gratified that you have carried through this 
undertaking. The beautiful manner in which the specimen is executed that you 
have sent me does great credit to engravers and publishers. It cannot be that 
our schools and colleges will fail to adopt this work, and bring it into very gen- 
eral circulation. I know of none which in all respects would supply its place." 

"The abridged but classical and excellent work of Butler, on Ancient Geogra- 
phy, which you are printing as an accompaniment to the maps, I consider one 
of the most attractive works of the kind, especially for young persons studying 
the classics, that has come under my notice. I wish you the most ample success 
in these highly useful publications." 



FRENCH AND SPANISH. 



BY A. BOLMAR. 



A COLLECTION of COLLOQUIAL PHRASES on every 

Topic necessary to maintain Conversation, arranged under differ- 
ent heads, with numerous remarks on the peculiar pronunciation 
md use of various words — the whole so disposed as considerably 
to facilitate the acquisition of a correct pronunciation of the 
French. By A. Bolmar. One vol. 18mo. 

A SELECTION of ONE HUNDRED PERRIN'S FABLES, 

accompanied by a Key, containing 1 the text, a literal and free 
translation, arranged in such a manner as to point out the differ- 

I ence between the French and the English idiom, also a figured 
pronunciation of the French, according to the best French works 
extant on the subject; the whole preceded by a short treatise on 
the sounds of the French language, compared with those of the 

I English. 

Les AVENTURES de TELEMAQUE par FENELON, ac- 
companied by a Key to the first eight books ; containing like the 
Fables — the Text — a Literal — and Free Translation ; intended as 
a Sequel to the Fables. 

The expression 'figured pronunciation,' is above employed to express that the 

words in the Key to the FrevchFabl.es are spelt andMivided as they are pronounced. 

It is what Walker has done in his Critical Pronouncing Dictionary ; for instance, 

he indicates the pronunciation of the word enough, by dividing and spelling it thus, 

e-nuf. In the same manner I indicate the pronunciation of the word comptaient 

*! thus, kon-te. As the understanding of the figured, pronunciation of Walker re- 

* quires the student to be acquainted toith the primitive sounds of the English vowels, 

he must likewise, before he can understand the figured pronunciation of the French, 

make himself acquainted with the 20 primitive sounds of the French voicels. This 

any intelligent person can get from a native, or from anybody toho reads French 

' well, in a few hours. 

A COMPLETE TREATISE on the GENDERS of FRENCH 

NOUNS ; in a small pamphlet of fourteen pages. 

This little work, which is the most complete of the kind, is the 
fruit of great labor, and will prove of immense service to every 
learner. 

ALL THE FRENCH VERBS, both REGULAR and IR- 
REGULAR, in a small volume. 

The verbs etre to be, avoir to have, parler to speak, J&u'r to finish, recevoir 
to receive, vendre to sell, se lever to rise, se bien porter to be well, s'en aller 
to go away, are here all conjugated through — affirmatively — negatively — 
interrogatively — and negatively and interrogatively — an arrangement which 
will greatly facilitate the scholar in his learning the French verbs, and 
1 which will save the master the trouble of explaining over and over again 
what may be much more easily learned from books, thus leaving him more 
time to give his pupil, during the lesson, that instruction which cannot be 
found in books, but which must be learned from a master. 



| NEUMAN'S SPANISH and ENGLISH DICTIONARY. 

New Edition, in one vol. 16mo. 



MECHANICS, MANUFACTURES, & c . 



A PRACTICAL TREATISE on RAIL-ROADS, and INTE- 
RIOR COMMUNICATION in GENERAL— containing an 
account of the performances of the different Locomotive En- 
gines at, and subsequent to, the .Liverpool Contest ; upwards of 
two hundred and sixty Experiments, with Tables of the com- 
parative value of Canals and Rail-roads, and the power of the 
present Locomotive Engines. By Nicholas Wood, Colliery 
Viewer, Member of the Institution of Civil Engineers, &c. 
8vo. With plates. 

" In this, the able author has brought up his treatise to the date of the latest 
improvements in this nationally important plan. We consider the volume to 
be one of great general interest."— Lit. Gaz. 

" We must, in justice, refer the reader to the work itself, strongly assuring 
him that, whether he be a man of science, or one totally unacquainted with its 
technical difficulties, he will here receive instruction and pleasure, in a degree 
which we have seldom seen united before." — Mtmthly Review. 

REPORTS on LOCOMOTIVE and FIXED ENGINES. By 
J. Stephenson and J. Walker, Civil Engineers. With an 
Account of the Liverpool and Manchester Rail-road, by H. 
Booth. In 8vo. With plates. 

MILLWRIGHT and MILLER'S GUIDE. By Oliver Evans. 

New Edition, with additions and corrections, by the Professor 
of Mechanics in the Franklin Institute of Pennsylvania, and a 
description of an improved Merchant Flour-Mill, with engrav- 
ings, by C. & O. Evans, Engineers. 

The NATURE and PROPERTIES of the SUGAR-CANE, 

with Practical Directions for its Culture, and the Manufacture 
of its various Products; detailing the improved Methods of Ex- 
tracting, Boiling, Refining, and Distilling; also descriptions of 
the Best Machinery, and useful Directions for the general Man- 
agement of Estates. By George Richardson Porter. 

" This volume contains a valuable mass of scientific and practical informa- 
tion, and is, indeed, a compendium of everything interesting relative to colonial 
agriculture and Manufacture." — Intelligence. 

" We can altogether recommend this volume as a most valuable addition to 
the library of the home West India merchant, as well as that of the resident 
planter." — Lit. Gazette. 

ELEMENTS of MECHANICS. By James Renwick, Esq. 

Professor of Natural and Experimental Philosophy, Columbia 

College, N. Y. In 8vo. with numerous engravings. 

" We think this decidedly the best treatise on Mechanics, which has issued 
from the American press, that we have seen ; one, too, that is alike creditable 
to the writer, and to the state of science in this country." — <im. Quar. Review. 

TREATISE on CLOCK and WATCH-MAKING, Theoretical 
and Practical, by Thomas Reid, Edinburgh Honorary Member 
of the Worshipful Company of Clock-Makers, London. Royal 
8vo. Illustrated by numerous plates. 



Statural Hfetorg **tt PuiosoirfiS- 



GEOLOGICAL MANUAL, by H. T. De la Beche, F. R. S., 

F. G. S., Mem. Geol. Soc. of France. In 8vo. With 104 Wood 
Cuts. 

" A work of first-rate importance in the science to which it relates, and which 
must henceforth take its place in the Library of every student in Geology."— 
Phil. Magazine. 

ELEMENTS of PHYSICS, or NATURAL PHILOSOPHY, 
GENERAL and MEDICAL, explained independently of 
TECHNICAL MATHEMATICS, and containing New Dis- 
quisitions and Practical Suggestions. By Neill Arnott, M. D. 
Second American from the fourth London edition, with Addi- 
tions by Isaac Hays, M. D. 
" Dr. Anion's work has done for Physics as much as Locke's Essay did for 

the science of mind." — London University Magazine. 
"We may venture to predict that it will not be surpassed."— Times. 
" Dr. A. has not done less for Physics than Blackstone did for the Law."— 

Morning Herald. 
" Dr. A. has made Natural Philosophy as attractive as Buffon made Natural 

History." — French Critic. 
" A work of the highest class among the productions of mind."— Courier. 
44 We regard the style and manner as quite admirable." — Morning Chronicle. 
44 As interesting as novel-reading." — Athenmum. 
44 Never did philosophic hand wield a pen more calculated to win men to be 

wise and good." — Edinburgh Observer. 
44 Of this valuable, or we might say, invaluable work, a second edition has 

been speedily demanded by the public voice."— Lit. Gaz, 

ARNOTT'S ELEMENTS of PHYSICS. Vol. H. Part I. 

Containing Light and Heat. 

44 Dr. Arnott's previous volume has been so well received, that it has almost 
banished all the flimsy productions called popular, which falsely pretend to strip 
science of its mysterious and repulsive aspect, and to exhibit a holiday apparel. 
The success of such a work shows most clearly that it is plain but sound know- 
ledge which the public want." — Monthly Review. ^ 

AMERICAN ORNITHOLOGY, or NATURAL HISTORY 
of BIRDS, inhabiting the UNITED STATES. By Charles 
Lucien Bonaparte ; designed as a continuation of Wilson's 
Ornithology, Vols. I. II. and III. 

%* Gentlemen who possess Wilson, and are desirous of rendering the 
work complete, are informed that the edition of this work is very small, 
and that but a very limited number of copies remain unsold. Vol. IV. in 
the Press. 

A DISCOURSE on the REVOLUTIONS of the SURFACE 

OF THE GLOBE AND THE CHANGES THEREBY PRODUCED IN 

the ANIMAL KINGDOM. By Baron G. Cuvier. Trans- 
lated from the French, with Illustrations and a Glossary. In 
12mo. With Plates. 

" One of the most scientific and important, yet plain and lucid works, which 

adorn the age." Here is vast aid to the reader interested in the study of 

nature, and the lights which reason and investigation have thrown upon the 
formation of the universe." — New Monthly Magazine. 



CHEMISTRY, 



THE CHEMISTRY OP THE ARTS, on tlie basis of Gray's 
Operative Chemist, heing an Exhibition of tlxe Arts and 
Manufactures dependent on Chemical Principles, with 
numerous Engravings, hy ARTHUR L. PORTER, M. D. 
late Professor of Chemistry, <fcc. in the University of Ver* 
mont. In Svo. With numerous Plates. 

The popular and valuable English work of Mr. Gray, which forms the 
groundwork of the present volume, was published in London in 1829, and 
designed to exhibit a systematic and practical view of the numerous Arts and 
Manufactures which involve the application of Chemical Science. The au- 
thor himself, a skilful, manufacturing, as well as an able, scientific chemist, 
enjoying the multiplied advantages afforded by the metropolis of the greatest 
manufacturing nation on earth, was eminently qualified for so arduous an 
undertaking, and the popularity of the work in England, as well as its 
intrinsic merits, attest the fidelity and success with which it has been ex- 
ecuted. In the work now offered to the American public, the practical 
character of the Operative Chemist has been preserved, and much extend- 
ed by the addition of a great variety of original matter, by numerous cor- 
rections of the original text, and the adaptation of the whole to the state 
and wants of the Arts and Manufactures of the United States. Among the 
most considerable additions will be found full and extended treatises on the 
Bleaching of Cotton and Linen, on the various branches of Calico Printing, 
on the Manufacture of the Chloride of Lime, or Bleaching Powder, and 
numerous Staple Articles used in the Arts of Dying, Calico Printing, and 
various other processes of Manufacture, such as the Salts of Tin, Lead, 
Manganese, and Antimony; the most recent Improvements on the Manu- 
facture of the Muriatic, Nitric, and Sulphuric Acids, the Chromates of 
Potash, the latest information on the comparative Value of Different Va- 
rieties of Fuel, on the Construction of Stoves, Fire-Places, and Stoving 
Rooms, on the Ventilation of Apartments, &c. &c. The leading object has 
been to improve and extend the practical character of the Operative Chem- 
ist, and to supply, as the publishers flatter themselves, a deficiency which 
is felt by every artist and manufacturer, whose processes involve the prin- 
ciples of chemical science, the want of a Systematic Work which should 
embody the most recent improvements in the chemical arts and mani|fac- 
tures, whether derived from the researches of scientific men, or the ex- 
periments and observations of the operative manufacturer and artisans 
themselves. 



CHEMICAL MANIPULATION. Instruction to Students on 
the Methods of performing Experiments of Demonstra- 
tion or Research, with accuracy and success. By MICHAEL 
FARADAY, F. R. S. First American, from the second 
London edition, with Additions hy J. K. MITCHELL, M. D. 

" After a very careful perusal of this work, we strenuously recommend it, as 
containing the most complete arid excellent instructions for conducting chemical 
experiments. There are few persons, however great thr-ir experience, who may 
not gain information in many important particulars; and for ourselves, we beg 
most unequivocally to acknowledge that we have acquired many new and im- 
portant hints on subjects of even every-day occurrence." — Philosophical Mag 

" A work hitherto exceedingly wanted in the laboratory, equally useful to the 
proficient and to the student, and eminently creditable to the industry and skill 
of the author, and to the school whence it emanates." — Journal of Science and 
Arts. 



ANATOMY. 

DIRECTIONS for MAKING ANATOMICAL PREPARA- 
TIONS, formed on the basis of Pole, Marjolin and Breschet, 
and including the new method of Mr. Swan, by Usher Parsons, 
M. D. Professor of Anatomy and Surgery. In 1 Vol. 8vo. with 
plates. 

A TREATISE on PATHOLOGICAL ANATOMY. By Wil- 
liam E. Horner, M. D. Adj. Prof, of Anatomy in the Univer- 
sity of Pennsylvania. 

"We can conscientiously commend it to the members of the profession, as a 
satisfactory, interesting, and instructive view of the subjects discussed, and as 
well adapted to aid them in forming a correct appreciation of the diseased con- 
ditions they are called on to relieve." — American Journal of the Medical Science, 
JVo. 9. 

By the same Author. 

A TREATISE on SPECIAL and GENERAL ANATOMY. 

Second edition, revised and corrected, in 2 Vols. 8vo. 

LESSONS in PRACTICAL ANATOMY, for the use of Dis- 
sectors. 2d edition, in 1 Vol. 8vo. 

SYSTEM of ANATOMY, for the use of Students of Medicine. 
By Caspar Wistar. Fifth edition, revised and corrected, by 
W. E. Horner, Adjunct Professor of Anatomy in the Univer- 
sity of Pennsylvania, In 2 Vols. 8vo. 

ELEMENTS of GENERAL ANATOMY, or a description of 
the Organs comprising the Human Body. By P. A. Beclard, 
Professor of Anatomy to the Faculty of Medicine at Paris. 
Translated by J. Togno. 

TREATISE on SURGICAL ANATOMY. By Abraham Col- 
les, Professor of Anatomy and Surgery, in the Royal College 
of Surgeons in Ireland, &c. Second American edition, with 
notes by J. P. Hopkinson, Demonstrator of Anatomy in the 
University of Pennsylvania, &c. &c. 

A TREATISE on PATHOLOGICAL ANATOMY. By E. 
Geddings, M. D. Professor of Anatomy in the Medical College 
of South Carolina. In 2 vols. 8vo. (In the press.) 

ELEMENTS OF MYOLOGY. By E. Geddings, M. D. illus- 
trated by a series of beautiful Engravings of the Muscles of the 
Human Body, on a plan heretofore unknown in this country. 
In the press. 

This work, in addition to an ample and accurate description of the gene- 
ral and special anatomy of the muscular system, will comprise illustrations 
of the subject from comparative anatomy and physiology, with an account 
of the irregularities, variations and anomalies, observed by the various an- 
cient and modern anatomists, down to the present time. 



MEDICINE. 



AMERICAN JOURNAL OF THE MEDICAL SCIENCES* ! 

i 

Piii>lislicd Quarterly* 

And supported by the most distinguished Physicians in the United States I 
nmong which are Professors Bigelow, Channing, Chapman, Coxe, De | 
Butts, Dewees, Dickson, Dudley, Francis, Gibson, Hare, Henderson f 
Horner, Hosack, Jackson, Macneven, Mott, Mussey, Physick, Potter I 
Sewall, Wafren, and VVorthington ; Drs. Daniell, Drake, Emerson, Fearn J 
Geddings, Griffith, Hale, Hays, Hayward, Ives, Jackson, Moultrie, Ware ] 
and Wright. It is published punctually on the first of November, Feb- 1 
ruary, May, and August. Each No. contains about 280 large 8vo. pages, J 
and one or more plates — being a greater amount of v matter than is fur- j 
nished by any other Medical Journal in the United Slates. Price $5 per I 
annum. 
The following' Extracts show the estimation in which this 

Journal is held in Europe : — 

"Several of the American Journals are before us. * * * * Of these the 
American Journal of the Medical Sciences is by far the better periodical ; it is, 
indeed, the best of the transatlantic medical publications; and, to make a com- 
parison nearer home, is in most respects superior to the great majority of Eu- 
ropean works of the same description "—The Lancet, Jan. J83i. 

"We need scarcely refer our esteemed and highly eminent cotemporary, [The I 
American Journal of the Medical Sciences,] from whom we quote, to our critical I 
remarks on the opinions of our own countrymen, or to the principles which in- | 
fljuence us in the discharge of our editorial duties." " Our copious extracts from 
his unequalled publication, unnoticing multitudes of others which come before 
us, are the best proof of the esteem which we entertain for his talents and abil- 
ities " — London Medical and Surgical Journal, March, 1830. 

"The American Journal of the Medical Sciences is one of the most complete 
and best ediied of the numerous periodical publications of the United States/' — 
Bulletin des Sciences Medicates, Tom. XIV. 

PATHOLOGICAL and PRACTICAL RESEARCHES on 

DISEASES of the BRAIN and SPINAL CORD. By John 

Abercrombie, M. D. 

"We have here a work of authority, and one which does credit to the author 
and his country." — North Amer. Med. and Surg. Journal. 

By the same Author. 

PATHOLOGICAL and PRACTICAL RESEARCHES o 
DISEASES of the STOMACH, the INTESTINAL 
CANAL, the LIVER, and other VISCERA of the 
ABDOMEN. 

"We have now closed a very long review of a very valuable work, and al- 
though we have endeavored to condense into our pages a great mass of import- 
ant matter, we feel that our author has not yet received justice."— Medico-Chir- 
urgical Review. 

A RATIONAL EXPOSITION of the PHYSICAL SIGNS 
of DISEASES of the LUNGS and PLEURA; Illustrating 
their Pathology and facilitating their Diagnosis. By Charles 
J. Williams, M. D. In 8vo. with plates. 

"If we are not greatly mistaken, it will lead to a better understanding, and 
a more correct estimate of the value of auscultation, than any thing that has 
yet appeared."— Am. Med. Journal. 

MANUAL of the PHYSIOLOGY of MAN; or a concise 
Description of the Phenomena of his Organization. By P. 
Hutin. Translated from the French, with Notes by J. Togno. 
In 12mo. 



XUEEDXCIN1!. 



The PRACTICE of PHYSIC. By W. P. Dewees, M. D. Ad- 
junct Professor of Midwifery, in the University of Pennsylva- 
nia, 2 Vols. 8vo. 

" We have no hesitation in recommending it as decidedly one of the best sys- 
tems of medicine extant. The tenor of the work in general reflects the highest 
honor on Dr. Dewees's talents, industry, and capacity for the execution of the 
arduous task which he had undertaken. It is one of the most able and satisfac- 
tory works which modern times have produced, and will be a standard authori- 
ty."— London Med. and Surg. Journal, Aug. 1830. 

DEWEES on the DISEASES of CHILDREN. 4th ed. In 8vo. 
The objects of this work are, 1st, to teach those who have the charge of 
children, either as parent or guardian, the most approved methods of se- 
curing and improving their physical powers. This is attempted by pointing- 
out the duties which the parent or the guardian owes for this purpose, to 
iiis interesting, but helpless class of beings, and the manner by which their 
uties shall be fulfilled. And 2d, to render available a long experience to 
lese objects of our affection when they become diseased. In attempting 
- -is, the author has avoided as much as possible, "technicality;" and has 
.' /en, if he does not flatter himself too much, to each disease of which 
treats, its appropriate and designating characters, with a fidelity that 
U prevent any two being confounded together, with the best mode of 
3 them, that either his own experience or that of others has sug- 

jiEWEES on the DISEASES of FEMALES, 3d edition, with 
Additions. In 8vo. 

A COMPENDIOUS SYSTEM OF MIDWIFERY; .chiefly 
designed to facilitate the Inquiries of those who may be pur- 
suing this Branch of Study. In 8vo. with 13 Plates. 5th edition, 
corrected and enlarged 

The ELEMENTS OF THERAPEUTICS and MATERIA 
MEDIC A. By N. Chapman, M. D. 2. vols. 8vo. 5th edition, 
corrected and revised. 

MANUAL of PATHOLOGY: containing the Symptoms, Di- 
agnosis, and Morbid Character of Diseases, &c. By L. Mar- 
tinet. Translated, with Notes and Additions, by Jones Quain. 
Second American Edition, 12mo. 

"We strongly recommend M. Martinet's Manual to the profession, and es- 
pocially to students; if the latter wish to study diseases to advantage, they 
should always have it at hand, both when at the bedside of the patient, and 
when making post mortem examinations." — American Journal of the Medical 
Sciences, JVo. J. 

CLINICAL ILLUSTRATIONS OF FEVER, comprising a 
Report of the Cases treated at the London Fever Hospital in 
1828-29, by Alexander Tweedie, M. D., Member of the Royal 
College of Physicians of London, &c. 1 vol. 8vo. 

" In short, the present work, concise, unostentatious as it is, would have led 
us to think that Dr. Tweedie was a man of clear judgment, unfettered by at- 
tachment to any fashionable hypothesis, that he was an energetic but judicious 
practitioner, and that, if he did not dazzle his readers with the brilliancy of the- 
. oretical speculations he would command their assent to the solidity of his didac- 
tic precepts."— Med. Chir. Journal. 



PHYSIOLOGICAL MEDICINE. 

HISTORY OF CHRONIC PHLEGMASIA, OR INFLAM- 
MATIONS, founded on Clinical Experience and Pathological 
Anatomy, exhibiting 1 a View of the different Varieties and 
Complications of these Diseases, with their various Methods 
of Treatment. By F. J. V. Broussais, M. D. Translated from 
the French of the fourth edition, by Isaac Hays, M. D. and 
R. Eglesfeld Griffith, M. D. Members of the American 
Philosophical Society, of the Academy of Natural Science, 
Honorary Members of true Philadelphia Medical Society, &c. 
&c. In 2 vols. Svo. 

EXAMINATION OF MEDICAL DOCTRINES AND SYS- 
TEMS OF NOSOLOGY, preceded by Propositions contain- 
ing the Substance of Physiological Medicine, by J. F. V 
Broussais, Officer of the Royal Order of the Legion of Hon- 
or ; Chief Physician and First Professor in the Military Hos- 
pital for Instruction at Paris, &c. Third edition. Translated 
from the French, by Isaac Hays, M. D. and R. E. Grif- 
fith, M. D. In 2 vols. 8vo. h% the press. 

A TREATISE ON PHYSIOLOGY, Applied to Pathology. 

By F. J. V. Broussais, M. D. Translated from the French, 

by Drs. Bell and La Roche. 8vo. Third American edition, 

witli additions. 

"Wo cannot too Btrongly reeommend the present work to the attention of 
our readers, and indeed of all those who wish to study physiology as it ought 
tone studied, in its application to the science of disease." "We may safely 
aay that he has accomplished his task in a most masterly manner, and thus 
established his reputation as a most excellent physiologist and profound pathol- 
ogist." — North American Med. and Surg. Journ. Jan. 1^7. 

THE PRINCIPLES AND PRACTICE OF MEDICINE. By 
Samuel Jackson, M. D. Adjunct Professor of Medicine in the 
. University of Pennsylvania. 8vo. 

THE PRACTICE OF MEDICINE, upon the Principles of 
the Physiological Doctrine. By J. G. Coster, M. D. Trans- 
lated from the French. 

An EPITOME of the PHYSIOLOGY, GENERAL ANA- 
TOMY, and PATHOLOGY of BICHAT. By Thomas 
Henderson, M. D. Professor of the Theory and Practice of 
Medicine in Columbia College, Washington City. 8vo. 

" The Epitome of Dr. Henderson ought and must find a place in the library 
of every physician desirous of useful knowledge for himself, or of being instru- 
mental'in imparting it to others, whose studies he is expected to superintend." 
—N. J3. Med. and Surg. Journ. No. 15. 

A TREATISE on FEVER, considered in the spirit of the new 
medical Doctrine. By J. B. Boisseau. Translated from the 
French. In the Press. 



MEDICINE AND SURGERY. 

A TREATISE on FEVER. By Southwood Smith, M. D., 

Physician to the London Fever Hospital. 

" No work has been more lauded by the Reviews than the Treatise on Fevers, 
by Southwood Smith. Dr. Johnson, the editor of the Medico-Chirurgical lie- 
view, says, ' It is the best we have ever perused on the subject of fever, and in 
our conscience, we believe it the best that ever flowed from the pen of physician 
in any age or in any country.' " — Jim. Med. Journ. 

An ESSAY on REMITTENT and INTERMITTENT DIS- 
EASES, including generically Marsh Fever and Neuralgia — 
comprising under the former, various Anomalies, Obscurities, 
and Consequences, and under a new systematic View of the 
latter, treating of Tic Douloureux, Sciatica, Headache, Oph- 
thalmia, Toothache, Palsy, and many other Modes and Conse- 
quences of this generic Disease; by John Macculloch, M. D., 
F. R. S. &c. &c. 

44 In rendering Dr. Macculloch's work more accessible to the profession, we are 
conscious that we are doing the state some service."— Med. Chir. Review. 

" We most strongly recommend Dr. Macculloch's treatise to the attention of 
our medical brethren, as presenting a most valuable mass of information, on a 
most important subject."— J\T. A. Med. and Surg. Journal. 

A PRACTICAL SYNOPSIS OF CUTANEOUS DISEASES, 
from the most celebrated Authors, and particularly from Docu- 
ments afforded by the Clinical Lectures of Dr. Biett, Physician 
to the Hospital of St. Louis, Paris. By A. Carman, M. D. 
and H. E. Schedel, M. D. 

" We can safely recommend this work to the attention of practitioners as con- 
taining much practical information, not only on the treatment, but also on the 
causes of cutaneous affections, as being in fact the best treatise on diseases of 
the skin that has ever appeared." — American Journal of the Medical Sciences, No. 5. 

SURGICAL MEMOIRS OF THE RUSSIAN CAMPAIGN. 
Translated from the French of Baron Larrey. Nearly ready. 

LECTURES ON INFLAMMATION, exhibiting a view of 
the General Doctrines, Pathological and Practical, of Medical 
Surgery. By John Thompson, M. D., F. R. S. E. Second 
American edition. 

THE INSTITUTES AND PRACTICE OF SURGERY; 
being the Outlines of a Course of Lectures. By W. Gibson, 
M. D. Professor of Surgery in the University of Pennsylvania. 
3d edition, revised, corrected, and enlarged. In 2 vols. 8vo. 

PRINCIPLES OF MILITARY SURGERY, comprising Ob- 
servations on the Arrangements, Police, and Practice of Hos- 
pitals, and on the History, Treatment, and Anomalies of Va- 
riola and Syphilis; illustrated with cases and dissections. By 
John Hennen, M. D., F. R. S. E. Inspector of Military Hos"- 
pitals — first American from the third London edition, with the 
Life of the Author, by his son, Dr. John Hennen. 

"The value of Dr. Hennen's work is too well appreciated to need any praise 
of ours. We were only required then, to bring the third edition before the 
notice of our readers; and having done this, we shall merely add, that the vol- 
ume merits a place in every library, and that no military surgeon ought to be 
without it." — Medical Gazette. 



MEDICINE, SURGERY, &c. 

SURGICAL MEMOIRS of the CAMPAIGNS of RUSSIA, 
GERMANY, and FRANCE. Translated from the French 
of Baron Larrey. In 8vo. with plates. 

A MANUAL of MEDICAL JURISPRUDENCE, compiled 
from the best Medical and Legal Works ; comprising an ac-> 
count of— I. The Ethics of the Medical Profession ; II. Char- 
ters and Laws relative to the Faculty ; and III. All Medico- 
legal Questions, with the latest Decisions : being an Analysis 
of a course of Lectures on Forensic Medicine. By Michael 
Ryan, M. D. Member of the Royal College of Physicians in 
London, &c. First American edition, with additions, by R. 
Eglesfield Griffith, M. D. In 8vo. 

''There is not a fact of importance or value connected with the science 
of which it treats, that is not to be found in its pages. The style is unam- 
bitious but clear and strong, and such as becomes a philosophic theme." — 
Mvnthly Review. 

"It is invaluable to Medical Practitioners, and may be consulted safely 
by the Legal Profession." — Weekly Dispatch. 

DIRECTIONS for MAKING ANATOMICAL PREPARA- 
TIONS, formed on the basis of Pole, Marjolin, and Breschet, 
and including the new method of Mr. Swan : by Usher Par- 
sons, M. D. Professor of Anatomy and Surgery. In 1 vol. 8vo. 
with plates. 

"It is compiled and prepared with judgment, and is the best and most 
economical companion the student can possess to aid him in the pursuit of 
this delightful department of his labors." — Boston Med. & Surg. Journal, 
Sept. 27, 1831. 

"This is unquestionably one of the most useful works on the preparation 
of Anatomical Specimens ever published. It should be in the hands of 
every lover of Anatomy ; and as attention now is more directed to the 
formation of museums, it will be found a very valuable book. Nothing is 
omitted that is important, and many new formulae are introduced, derived 
from the author's experience, and from rare books, which he has had the 
industry to collect." — N. Y. Medical Journal, August, 1831. 

A PRACTICAL GUIDE to OPERATIONS on the TEETH, 
by James Snell, Dentist. In 8vo. with plates. 

PRINCIPLES of PHYSIOLOGICAL MEDICINE, including 
Physiology, Pathology, and Therapeutics, in the form of Pro- 
positions ; and Commentaries on those relating to Pathology, by 
F. J. V. Broussais ; translated by Isaac Hays, M. D. and R. 
E. Griffith, M. D. In 8vo. 

ELEMENTS of PHYSIOLOGY, by Robley Dunglison, M. D. 
In 2 vols. 8vo. with numerous illustrations. (In the press.) 

PRINCIPLES of SURGERY, by John Syme, Professor of Sur- 
gery in the University of Edinburgh. In 8vo. 

PRACTICAL REMARKS on the NATURE and TREAT- 
MENT of FRACTURES of the TRUNK and EXTREM- 
ITIES ; by Joseph Amesbury, Surgeon. In 8vo. with plates 
and wood-cuts. (In the press.) 



i 



MSBICINE. 



The ANATOMY, PHYSIOLOGY, and DISEASES of the 

TEETH. By Thomas Bell, F. R. S., F. L. S. &c. In 1 vol. 

8vo. With Plates. 

" Mr. Bell has evidently endeavored to construct a work of reference for the 
practitioner, and a text-book for the student, containing a ' plain and practical 
digest of the information at present, possessed on the subject, and results of the 
author's own investigations and experience.' " * * * " We must now take leave 
of Mr. Bell, whose work we have no doubt will become a class-book on the im- 
portant subject of dental surgery."— Medico- Chirurgical Review. 

" We have no hesitation in pronouncing it to be tbe best treatise in the Eng- 
lish language."— North American Medical and Surgical Journal, No. 19. 

AMERICAN DISPENSATORY. Ninth Edition, improved 
and greatly enlarged. By John Redman Coxe, M. D. Professor 
of Materia Medica and Pharmacy in the University of Penn- 
sylvania. In 1 vol. 8vo. 
%* This new edition has been arranged with special reference to the 

recent Pharmacopoeias, published in Philadelphia and New- York. 

ELLIS' MEDICAL FORMULARY. The Medical Formulary, 
being a collection of prescriptions derived from the writings 
and practice of many of the most eminent Physicians in Ame- 
rica and Europe. By Benjamin Ellis, M. D. 3d. edition. 
With Additions. 

"We would especially recommend it to our brethren in distant parts of the 
country, whose insulated situations may prevent them from having access to the 
many authorities which have been consulted in arranging the materials for this 
work. ,, — Phil. Med. and Phys. Journal. 

MANUAL of MATERIA MEDICA and PHARMACY. By 
H. M. Edwards, M. D. and P. Vavasseur, M. D. comprising- 
a concise Description of the Articles used in Medicine ; their 
Physical and Chemical Properties ; the Botanical Characters of 
the Medicinal Plants ; the Formulae for the Principal Officinal 
Preparations of the American, Parisian, Dublin, &c. Pharma- 
copoeias ; with Observations on the proper Mode of combining- 
and administering Remedies. Translated from the French, 
with numerous Additions and Corrections, and adapted to the 
Practice of Medicine and to the Art of Pharmacy in the United 
States. By Joseph Togno, M. D. Member of the Philadelphia 
Medical Society, and E. Durand, Member of the Philadelphia 
College of Pharmacy. 

"It contains all the pharmaceutical information that the physician can desire, 
and in addition, a larger mass of information, in relation to the properties, &c. 
of the different articles and preparations employed in medicine, than any of the 
dispensatories, and we think will entirely supersede all these publications in the 
library of the physician.'" — Jim. Jeum. of the Medical Sciences. 

MEMOIR on the TREATMENT of VENEREAL DISEASES 
without MERCURY, employed at the Military Hospital of 
the Val-de-Grace. Translated from the French of H. M. J. 
Desruelles, M. D. &c. To which are added, Observations by 
G. J. Guthrie, Esq. and various documents, showing the results 
of this Mode of Treatment, in Great Britain, France, Ger- 
many, and America. 1 vol. 8vo. • 



PREPARING FOR PUBLICATION 

BY CAREY & LEA, 
CYCLOPAEDIA 



•7 



OF 



PRACTICAL MEDICINE; 

COMPRISING 

TREATISES ON THE NATURE AND TREATMENT OF DISEASES, 

MATERIA MEDICA AND THERAPEUTICS, 

MEDICAL JURISPRUDENCE, &c 

EDITED BY 

JOHN FORBES, M. D. F. R. S. Physician to the Chichester Infirmary, &c. 
ALEXANDER TWEEDIE, M. D. Physician to the London Fever Hos- 
pital, &c. 

JOHN CONOLLY, M. D. Professor of Medicine in the London Univer- 
sity, &c. 

WITH THE ASSISTANCE OF THE FOLLOWING PHYSICIANS: 



JAMES APJOHN, M. D. M. R. I. A. Professor of 
Chemistry to the Royal College of Surgeons in 

JAMES L BARDSLEY, M. D. Physician to the 
Manchester Roval Infirmary Dispensarv, &c. 

EDWARD BARLOW, M. D. Physician to the 
Ba'h United Hospital and Infirmary. 

R. H. BRABANT, M. I). Devizes. 

JOSEPH BROWN, M. O. Physician to the Sunder- 
land and Bishopwearmouth Infinnary. 

THOMAS H. BIRDER. M. D. Member of the 
Rnval Colle_ r e of Physicians, London. 

JOHN BURNS, M. D. Physician to the Carey- 
S reef Dispensary. 

H. W. CARTER. M. D. F. R. S. E. Physician to 
the Kent and Canterbury Hospital. 

JOHN CHEYNE, M. D. F. R. S. E. M. R. I. A. 
Phvsic'ian-Geueral to the Forces in Ireland, &c&c. 

JAMES CLARK, M. D. Physician to St. George's 
Infirmary. &c. fee. 

JOHN CCENDINNING, M. D. Fellow of the 
Roval College of Physicians. London. 

JOHN CRAMPTON, M. D. M. R. I. A. Kind's Pro- 
fessor of Materia Medica, Physician to Steevens's 
Hospital, & c . &c Dublin. 

ANDREW CRAWFORD, M. D. Physician to the 
Hampshire County Hospital, Winchester. 

WILLIAM CUMIN, M. D. Glasgow. 

JAMES CUSACK, M. B. Steevens' Hospital, Dub- 
lin. 

JOHN OAR WALL, M. D. Physician to the Gene- 
ral Dispensarv, Birmingham. 

D. D. DAVIS, M. D. M. R. S. L. Professor of Mid- 
wifery in the London University. 

JOHN ELLIOTSON. M. D. F. R. S. Physician to 
St. Thomas's Hospital. 

R. J. GRAVES, M. D. M. R. I. A. King's Professor ! 
of the Institutes of Medicine, Physician to the 
Mea'h HospPal and County of Dublin Infirmary. ' 

GEORGE GREGORY, M. D. Physician to the 
Small-Pox Hospital. 

MARSHALL HALL, M. D. F. R. S. E. Member of 
the Royal College of Physicians, London. &c. &c. 

THOMAS HANCOCK, M. D. Liverpool, Member] 
of the Royal College of Physicians, London. 1 



CHARLES HASTINGS, M. D. Physician to the 
Worcester General Infirmary. 

B1SSET HAWKINS, M. 1). Fellow of the Royal 
College of Physicians, Professor of Materia Medi- 
ca and Therapeutics in Kind's College, London. 

J. HOPE, M. D. Member of the Royal College of 
Physicians, London. 

ARTHUR JACOB, M. D. M. R. I. A. Professor of 
Anatomy to the Royal College of Surgeons in 
Ireland. 

ROBERT LEE, M. D. F. R. S. Physician to the 
British Lyine-in Hospital. 

CHARLES LOCOCK, M. D. Physician to the 
Westminster General Lying-in Hospital, &c. &c. 

II. MARSH, M. D. M. R. I. A. Professor of the 
Principles and Practice of Medicine to the Royal 
College of Surgeons in Ireland, &c Dublin. 

JONES QUAIN, M. B. Lecturer on Anatomy and 
Physiology in the Medical School, Aldersgate- 
Street. 

J. C. PRICHARD, M. I). F. R. S. Physician to the 
Infirmary and to St. Pe'er's Hospital, Bristol. 

ARCHIBALD ROBERTSON, M. 1). Physician to 
the Northampton General Infirmary. 

P. M. ROGET, M. D. Sec. R. S. Consulting Physi- 
cian to the Queen Charlotte's Lying-in Hospital 
and so the Northern Dispensary, &c. &c. 

JOHN SCOTT, M. D. Edinburgh. 

WILLIAM STOKES, M.D. Physician to the Meath 
Hospital. 

WILLIAM STROUD, M. D. Physician to the Nor- 
thern Dispensary. 

A. T. THOMSON, M. D. F. L. S. Professor of Ma- 
teria Medica in the London University. 

THOMAS THOMSON, M. D. F. R. S. L. &E. Re- 
gius Professor of Chemistry in the University of 
Glasgow, &c. &c. 

T. J. TODD, M. D. Physician to the Dispensary, 
Brighton. 

RICHARD TOWNSEND, A. B. M. D. M. R. LA. 
Fellow of the King and Queen's College of Phy- 
sicians, Dublin. 

CHARLES J. B. WILLIAMS, M. D. London. 
&c. &c. &c 



To adapt the above work to the wants of this country, the publishers 
have engaged the assistance of many of our most eminent physicians, and 
they pledge themselves that no exertion shall be spared to render it wor- 
thy of patronage. It will be published in monthly numbers, price 50 cts. 
COO pages each. 



LB N 



